175MHz and 64 MB ram are enough for many things (but you better avoid to open many screens, reduce use of MUI textures and so on). I had a similar setup (had SCSI drives thoufg and my Blizzard ran at 200MHz) and it was convenient. The difference to the 68040/25 was huge - the JIT is more than twice as fast as the real 68040.
I once did a brief comparision of my setups:
http://via.i-networx.de/EN/bench_en.html
