Yes, they make a worthy replacement on the Amiga for most uses, because the main issue with flash memory is writing to it - reading from it is fast and can be done as much as you like, but writing to it can be slow (depending on the card and other factors) and will eventually "wear out" the card after many repeated write cycles. The thing about the Amiga is that it doesn't write to the drive the whole time like most other operating systems - normally it'll just read. There's no virtual memory, no automatically remembering icon or window positions, last accessed files and applications etc. which would normally cause frequent writes to the drive on other systems.
Any decent flash card can rewrite the same blocks tens of thousands of times without any issues, and that's more than you'll ever need on your Amiga...
