A very fast response, wow 
There are still many Amiga users around, I see 
OK, I understand that the best solution for my A3000/040 and A1200/030 is AmigaOS3.9 but... What I can really do better with the new operating system than 3.1?
Jen
OS3.9 is really nice - but in my experience and usage, I do not like running it on anything less than an 040. It felt pretty slow on my 40mhz 030 equipped A1200 when I had it and I recently installed 3.9 on my 25mhz A3000 - to which I quickly un-installed it and went back to 3.1. Using a modestly sized hard drive, I did not need, nor enjoy 3.9's automatic resetting of the computer and it's fancy icon scheme is too slow for my tastes on an 030.
3.1 on an 030 is excellent though! IF you want 3.9 like operations, there's tons of "plug-ins" and apps you can download from Aminet, etc. if you want to tweak 3.1 'til your hearts content. That's what I've done and am extremely happy with the results.