Well your analogy is the basic and I'd imagine the one that most people use and probably based their results in the survey, however if you want to be really in depth about it then no there's other things to factor for a true RPI, for that you have to take into account production costs involved in producing that imagery including the time spent uploading

Yes of course, it's gross RPI. But comparing RPIs over sites, net RPI can be discarded since it belongs to an image, not to the site. If you define RPI as yield per specific image (over all sites), then you have to take costs into account to get the actual yield of course. Or rather all the images that belong to the same shoot and share the same costs.

I don't think most modest microstockers (like myself) want to do that since they only count their marginal costs. Those beautiful tropical beach shots are just a side product of a beach holiday they would have taken anyways. Or do an assignement and do some stock at the side, like on the end of the last film roll.
I guess if they would count the total production cost, included camera, space and equipment write-off, they would discover that they lose a lot on microstock. Some even buy a 20MP Canon D5MKII just for stock, when a < 1000$ D90 is good enough. You don't need a D5 for your holiday shots and your weddings. It could only be OK if your volume exceeds 1000-1500 new stockworthy accepted shots per year.

Since the vast majority of microstockers just counts their marginal costs and doesn't count their postprocessing/upload time, the professional stockers that have to count all their costs are at a very big disadvantage. The clever ones will need to do assignments, events, weddings etc... at the side to survive.

Masnick on Techdirt wrote about The Grand Unified Theory On The Economics Of Free in the music industry. Since digital music is in endless supply (like images) and the marginal cost is almost zero, those products will tend to be priced zero. A musician should make his income from side-effects that are scarce, like concerts, concert tickets, merchandise, backstage passes etc...
Applied to photography, you could argue that prices still will go down until they fall below the cost of even the cheapest production. A photographer can then only survive by his assignments, and use the prestige of being on stock as a marketing advantage against other local assignment photographers.

Finally, there is the often ignored aspect of globalization. I wrote about this 3 years ago on Talkmicro and most had to laugh. Just go to any site forum and look at the new contributors. Most are from Serbia, Ukraine, Russia, Croatia, Slovenia, Poland, and recently the Chinese started to pour in. Those are countries with a cost of living that is a fraction of that of the industrialized West, but they get the same price for their photos as Western photographers. The production cost of a shoot is much lower there and in the limit, they will dominate the scene. Devaluing the dollar is a great move from Obama, so the West-Europeans will be the first to go.

2 cents 

One things for sure judging by some comments, a lot of people don't understand or have a different perspective on how RPI works.

RPI per month on a particular site is the total income for that month on the site, divided by the number of images online at the end of that month. Correct?

This measure should not be confounded with income/download which would be the same as RPI if all your shots were downloaded in the same amount. You can have a very high income/download but a low RPI if only 10% of your port sells well.

Yes, I believe it is a fact. .... From the top 4 sites and 204 non-exclusive photographers, 93 said iStock gave the highest RPI.

Yes, I read it in the other thread. I'm a methodology freak (probably a handicap left over from a previous job) but with 93 out of 204 = 46%, istock doesn't have the highest RPI for most, not even for the majority. Given a margin for a low confidence limit on a sample of just 204, you can safely say that istock gives the highest RPI for half the respondents.

I always loved statistics and the result raises some interesting questions, for instance the correlation between the reported RPI and portfolio size on every site. But that takes us too far, and the question wasn't in the survey.

If I can just hold out 3 more years, maybe I CAN get a D3X!

Yeah right, a D3X for microstock 
6MP or 24MP, in the limit you just get the same 0.25c for a subscription download.

And big watermark wont help, too?

Why don't you ask this on the istock forum? They are the only ones that can answer.

I am exclusive videographer in istock and i plan to make showreel and upload it to vimeo. So-if i upload any of my clips to vimeo, i am immediately violating my exclusivity contract with istock?

Yes. Be grateful to Leaf for warning about this.

You cannot be certain she�s a she and not a he, just because the name is randys"grandma". Not nowadays.

It's a she. There is one of these crazy threads on SS where Rinder asked to tell your life story and she's there.

Let the sales start rolling in now!

Don' be too optimistic. After an x-tended license on Feb 17, just 3 subscription sales and the last one was on March 02. Seems the Photos.com channel got stuck...

FXP must be enabled on both FTP servers, which obviously includes the microstock agency FTP servers in this situation. Flemmish, have you successfully uploaded files with FXP before? I read that it opens some vulnerabilities, so I don't expect microstock agencies would have it enabled.

No, it didn't work on hostgator from my side. My server only wants to deal in and out with my own IP, obviously the IP that I logged in with. Perhaps it can be reconfigured since I put security and restrictions maximum after an incident. I didn't check the hostgator forum yet.

wow, hey ! wait for me ...running behind all of you.. at
8380
3 months old and less than 40 images.

Post less, shoot more 

Who else?

http://twitter.com/flemishdreams

So they lie you right in the face?

No comment. 
Maybe not and I'm wrong. You found out yourself, right? 

Freebees are good for the traffic of the site, so they benefit everybody in the end. Thanks for being Mother Theresa.