I have to agree with that. A 68030 is as (in)compatible as the A1200's original 68020, it doesn't generate much heat (in contrast to a 68040) and it has a very good price/performance ratio. The only advantage of an 68040 would be that it is twice as fast (68030/50 vs. 68040/25), but for most of the things you have in mind, the 68030 should be sufficient.
web browsing, personal finance and word processing.
Don't try to do these things with an A1200, unless you are
very patient or willing to spend a fortune on upgrading the machine.
Web browsing without a graphics card is a real pain. Word processing would benefit from a faster cpu and a gfx card aswell. Better use your A2000 for stuff like that.
ROM 3.0 with OS3.1 or Rom 3.1 with OS3.9?
Kickstart 3.0 and OS 3.0 should be sufficient for retro-gaming, Scala and some basic networking stuff (e.g. drive sharing between the A1200 and the A2000).
It really seems that many pieces of softwares, especially games, do not work well with 68040/60 processors, even though they provide more speed.
That's right, but even a stock A1200 has a lot of problems running old games. Use WHDLoad to install your games to the HD and your problems are gone. Get a good degrader (I'd recommend T.U.D.E.) for the stuff not supported by WHDLoad.
