I must correct my enthusiasm with the following facts (which I don't understand for the most part):
- first, a bit of background: I purchased ClipWrap (CW) a while back and almost immediately found a problem with it dealing with my CX550V clips: sometimes, it would not convert clips. I reported this to the company developing it and they were very supportive, rapidly fixing the problem after I sent them a few clips. I have had no problem with the new version they have released recently.
- my discovery of Media Converter (MC) is serendipitous and although I installed it, there is no reason why I should use it rather than ClipWrap, but nonetheless, that's what I did ever since I installed it.
- I had not done any editing for a while, so I did not discover the following problem until now: when editing some of my HX5V clips (1080i60, AVCHD, stereo) with FCE, I noticed that some of the frames were green (like in "green screen"). I checked the .mov file using QuickTime (QT), and indeed I saw those frames there too (although this is a bit more difficult to see, as one has to step very carefully through the clip).
At first, I thought that maybe the camera had skipped frames due to its lower quality than the CX550V (or the type of SD card I was using), but I wanted to make sure that this was not a conversion problem, so I pulled back my disk image (glad I kept disks images even after conversion of the mts files into mov ones!) and tried a log and transfer (which I never use, as I just import the converted mov files, usually). Those clips looked fine, with no green frames. This seemed to point to a conversion issue with Media Converter.
Just to make sure, I converted the mts file with ClipWrap. Surprisingly (or maybe not), the resulting mov file was slightly bigger than the one generated by Media Converter. And it did not seem to contain any green frames.
Now comes the interesting parts:
1) I created a blank project in FCE in which I could compare two versions of the same clip: one converted by Clip Wrap, the other converted by Media Converter. The green frames still occurred in the MC version, but NOT AT THE SAME LOCATION as before! I tried this several time, creating new projects and closing FCE, and each time I checked the SAME Media Converted created clip, the green frames were located at different positions... I don't understand that, but the next bullet may shed some light on what is going on.
2) While I was stepping through the clips in FCE, I noticed something strange: clips created by MC had time stamps of the kind 8:1, 8:2, ..., 8:29, 9:0... while those created by CW had time stamps of the kind: 8:2, 8:4, ..., 8:58, 9:0... (as in, I show you every even field of each frame of your interlaced clip). This seems to match the info from QuickTime (well, not quite, but I'll get to that), which says that the CW converted movies are 29.97 fps ones, whereas those converted by MC are 59.94 fps ones. Remember the thread "Sony 1080/60i stored as 30p?" started by Eric? There, we learned that it is OK to have QT say that a 60i video is 29.97 fps. So indeed CW does a correct job. But what does MC do then? Why does it look to QT as a 60 fps movie and why does it look like a 30 field per second to FCE when imported in a 1080i60 project? I could try to make hypotheses, but I won't as it appears clear to me that Media Converter DOES NOT behave like ClipWrap after all, and in any case seems to do a mess.
So bottom line: if somebody has read the first post but did not bother to try understand what I was describing in the second: stay away from MC and buy ClipWrap.
If somebody has understood what I am describing in this post and knows exactly what is going on, I'd be happy to learn something.
Meanwhile, I have to reimport all my clips since mid-April and reconvert them with ClipWrap... 
