Amigas start to live with 68040 cpu, anything less is not interesting. With 040 OS is snappy no matter how much you tinker with it. Even Basic OS3.9 is poor with 68030
In
your opinion.
As the expansion bus Amigas are equipped with is at best an '030 bus, that notion is contestable.
And I was perfectly happy with the 14MHz '020 card I had in my A2000.
As to 3.9, I'd still prefer an enhanced version of 3.1.
3.9 is no longer available (legally).