I remember in a recent thread  Yuri stating  how difficult to get in to  big macro agencies like Getty, Corbis etc.
I wonder how difficult it actually  is to get  accepted by these big players
Of course I have the idea of their quality standards but if Yuri meant to say he couldn't get in(which I find very unlikely as  to my point of view he could easily pass their tests or applications )I don't know may be he find microstock more profitable but that's a different matter.
I would like those who are on these agencies  to share  their experience please.Also those who are planning to join.

I'm nowhere near qualifying to contribute to such agencies, but I can comment on Yuri's comments.

Yes, he could easily get accepted by Getty Images and Corbis if he wished. He has contributed photos in the macrostock market since he first began. He earned US$64,000 from microstock last month and US$80,000 in total. However, I understand the difference in earnings to be a reflection of the quantity of work he contributes to each market rather than the profitability of either one.

He has made recent comments about the profitability of microstock now that he is spending large amounts on his productions. See: http://www.microstockgroup.com/index.php?topic=3278.0

While he says he intends to continue contributing to both markets indefinitely, it's reasonable to expect he'll adjust the balance of what he contributes to each market to maximise his return on investment.

I don't know which agencies in the macrostock market Yuri uses, though I know many such agencies distribute directly to Getty, Corbis and Jupiter. This means that the photographer doesn't need to go directly to Getty et al, as distributing agencies can do it for them. To answer your question, I 'expect' this is the easiest way to get in, though I know at least some of these agencies are invitation only!

I'm slowly learning about the macrostock market, and each time I learn something new I realise how different it is from the microstock market.

I would consider a couple of points before I would try to "get in":
1.The revenue you can get from microstock is at least the same but in many cases much more than you can get from working with macros with the same number of images. It depends on what kind of stuff you do of course - but for regular plain non-fancy commercial/business/advertising stuff micros provide much better return.
2. It is a huge pain to submit to most macros - compared to that, submitting even to Istock is a breeze! The amount of bureaucracy you have to deal with is unbelievable. I suspect that spending that time producing more images makes more sense.
3. Many of macros require exclusivity - which means you'll be totally dependent on how their business is doing. All eggs in one basket kinda thing. Which I personally don't like.
So, I wouldn't call it a "step up" really. I depends on what kind of images you produce - if you're doing celebrity shots, editorial stuff, sports, events - there is a chance you'd do better on macros, I have heard people reporting that. It's not that hard to get in  - but it has to be worth the effort.
Personally I tried to work with some macros and midstock, and most of them were a disappointment - too time consuming, sales are few and apart. For the stuff that I do microstock is the best (so far:)), and I do get kicks from getting those "thank you" emails from people who would never be able to afford a nice piece of photography work otherwise.
As to what Yuri/Jacob does, I don't think it is hard for him "to get in" into macro business, maybe hard to do it on HIS terms:) And I am pretty sure he does some of it, but also I am pretty sure he knows pros and cons of it too. Micros are not inferior to macros - they are just different, like Wallmart is different from a fancy high-end department store... who do you think makes more money?...;-)