The software currently on offer at IOSpirit are "full products". What that means is, they are complete software products which are able to stand on their own two feet in their own right. Just because development is currently frozen, it doesn't make those products any less useful, and infact my experience of IOSpirit's software is that they are of excellent quality - I've been completely satisfied with all my purchases, and will continue to use the software regardless of whether development is continued or not. Hopefully all my IOSpirit software will work with OS4, too.
Also, since IOSpirit has only frozen new developments; in other words they haven't left the Amiga platform and are still operating, you still get support for their products.
I am dissapointed that development is currently frozen, but that's mainly because I'm so satisfied with what I've seen from IOSpirit so far - I'd love to see them develop further and continue to release new software. It'd be a shame if development was to remain frozen forever, but again that doesn't make my copy of FXPaint2 (for example) any less capable does it? I can still use it!
My advice is, if you're interested enough in IOSpirit's software that you'd be willing to pay for it, then definately buy it - you wont be dissapointed with the quality of the software. In so doing, you're supporting the developers and, hopefully, once OS4 is properly released we'll start to see more developments from IOSpirit again.
Brian