cordless screwdriver for trimmer?

Yes, but remember the power adapter will eventually cause some wear on the shaft body. (they have a warning about it). I opted for the drill press adapter, mainly because I have a lot of cases to run.

"Is a standard 180 rpm cordless screwdriver enough power for a forster trimmer"

That sorta depends on what you feel is "standard" power. Most will probably do fine, at least until the battery goes flat.

works for me

I use the Lee trimmer sets with a cordless screwdriver, no problem.