MicrostockGroup

If you open an older version of an eps or ai file in a newer version of illustrator, you'll get the [converted] tag on the end... just remove it if you need.

For removing those gradient bands I'd recommend exporting the JPEG as RGB if the illustrator file is in RGB mode and CMYK if it is in CMYK mode... I've done various tests with this and found quite dramatic differences if I set up in CMYK in illustrator and then export directly as an RGB JPEG vs. a CMYK JPEG.

Depending on the size of your art board you can alter the pixel count of your jpeg with the DPI... 300 DPI sometimes isn't high enough to get you to 6MP or 3000x2000pixels...usually I export at 450dpi for a 10"x10" art board giving 4500x4500pixels.

Hope this helps.

I prefer to open my AI files in Photoshop. That way I can set the exact pixel dimensions when opening. Using the EPS might cause the problem with the gradient, depending on your EPS settings.

Re: 300 dpi — The DPI is not what's important, it's the overall pixel dimension. What site(s) are you uploading to? iStock specifies their JPEGS to be 1900 x 2800, or the equivalent. This means if you multiply 1900 x 2800, you get <5.3 million. So as long as that number is above 5.3. million, you're good to go. You file could be 2350 x 2255, or 4000 x 1325, or anything. The DPI is irrelevant. Now, if you set your file size to 2800 x 1900, then change the DPI, the length and width will change. So watch out for that.

If you're using Save For Web in Illustrator, click on the Image Size tab and just make sure that those dimensions, when multiplied, are over 5.3 million.

As for the [converted] thing, go to your preferences in Illustrator an UNcheck "Append [Converted] Upon Opening Legacy Files." See if that works

Thanks for this - very helpful.  I've been saving as JPG from Illustrator, and was getting massive file sizes.  I keep the large ones for sites that ask for large jpgs, and then open in Photoshop and resize for smaller previews.
I never realised I could Save for Web and change the dimensions there.
Now I'm getting a 5Mp JPG for 600k instead of 3Mb, which will save hugely on my upload time - thank you!

I'm not sure what I should be setting as the "quality" of the export - any tips? 
I'm also getting an error on export saying that the dimensions exceed what "save for web" was designed for - I ignore it and carry on.  Just wondered if there's anywhere to change the default max?

Thanks!