Imatest - yes and no
After some research i couldn't find any other alternatives that seemed reasonable and bought Imatest and the SFRplus target for something north of $500 as a potentially "simple" solution to some objective results. The Imatest program and "documentation" are sort of a test solution to all things optical and it's up to the user to figure out what to do with it. I spent on the order of 40 hours testing and figuring out how the software worked before getting meaningful results.
Once on top of the learning curve the results for comparing lenses and bodies are very useful. but the resolution results are comparative (my results are similar to those of DP Review, but much lower than Photozone). Lighting is an important factor and i should probably invest in some lighting as well, but haven't. Because of camera to subject distance and lighting, testing long lenses is a challenge and i need multiple images to get a reasonable level of confidence.
I've used the results to select lenses, figure out which camera/lens combinations are most useful, refine technique, and determine if a lens is performing as it should and if it improved on repair (but you can only do this after developing your test/information base)
If you're going to invest a substantial amount of money in cameras and lenses, want the best results you can get, and can afford the time spent on the learning curve, then yes.
I think Imatest is really missing the boat by not offering a comprehensive and simplified package for photographer users.
Converters - 10 years ago on my EOS-3 and much more recently on 20D i thought converters were fine, but since then, the cameras are much closer to the capabilities of the lenses and the bar has been raised in the ability to examine images and make big prints.
One more thought - at f5.6 i'm willing to bet the there's little difference in resolution between the f2 and 2.8 200 with and without the converter. I'd love to be wrong.
