The Blizzard acclerator cards got around the problem by having buffered access to the A1200 motherboard, whereas the apollos had no such buffering...
As a consequence the Blizzard's access to anything on the motherboard (chip ram, custom chips, powerflyers etc) was slower than the Apollo's, however it did mean that the Blizzard's would run stable in machines with timing issues.
The Apollos however were technically faster, although could be unstable or just not work on unfixed boards...
I've never personally owned an Apollo card so I don't know the real difference in speed... But my boss/friend/Frank said the apollo transfer speeds were much faster when used in conjunction with a powerflyer.
