Well, one interesting thing I have not seen covered is what type of machine the SSD is going to be used in. The advantages of SSD are obviously a lot greater with a newer machine with a wider/faster data bus. I am guessing that anything (except horrendously cheap mobos) that supports SATA II/300 should see a better advantage.
Either way, seek times are a big advantage. Certain other things, such as (lack of) head movement are more of an advantage on a JFS partition than on an HPFS partition (due to fragmentation or lack thereof).
SSD's do definitely seem to decrease certain aspects of boot speed under OS/2 and eCS (especially since there are a "ton" of smaller files that need to be read; thus an SSD cuts the time down due to lack of R/W head movement) - but not all. Since Warp/eCS initialize almost everything during boot, there will still be delays in booting (while waiting for various services and hardware to be initialized - ie: things totally irrelevant to the data transfer and access speeds).
I am "guessing" that various applications can also benefit from SSDs, such as MySQL, Apache, DominoGo, etc... but on the other hand, those are also the applications that will shorten the SSD's life expectancy due to an increased amount of writes.
On that note, I suspect that OS/2 in general, would decrease the life of an SSD due to it's nature... for instance, if Warp/eCS is installed on an SSD, it will be writing to it quite a lot (as an example: every time you move, resize or change a folder, as it stores that stuff in the INI files). In that respect, I suspect that an SSD should also make the desktop a little bit more responsive (though perhaps not noticeably so, considering hard drives have come a long way, and their caches should be large enough to buffer such reads/writes).
-Rob