Not sure who did the measurement of "5x faster" - the general rule of thumb is "twice as fast with the accelerator you have".
Most 040 and 060 accelerators reduce the speed on the IDE to about 1MB per second. The top speed of 5.1MB per second is only reached with synconously-clocked 030 processors, for example the 42MHz models by M-Tec. Since 040/060 processors don't talk to the A1200 motherboard directly, but through a bus arbiter that also emulates the dynamic bus sizing of the 030 processor, they are losing an average of 1.5 clock cycles. I'd expect an average performance of 2.5MB per second on 040/060/PPC accelerators, which is "about twice as fast" as without express.
IDE-fix express is not as fast as the FastATA controller. However, it supports both 64-bit addressing modes (TD64 and NSD64) and no proprietary re-mapping of partitions and virtual harddrives. Further, it doesn't touch your RDB unless you tell it to (by clicking "save changes to drive" in HDToolbox). Also, if you have the FastATA, you won't be able to take advantage of the clockport-extender that will be out for this year's Xmas business (will allow you to connect up to four clockport devices in the A1200).
I have been asked if this product works in an A600 - it's only sold together with the express-adapter, which does NOT work in the A600. The IDE-adapter itself would, but it would be a waste to buy both, only to use one half of it. Also, the express-adapter must be installed in order to license the software, as it acts as a dongle. The software would come up as a demoversion on an A600.
Thanks for the support - and sorry for my continuous silence on any Amiga-forum in the past few months. I'm still extremely busy with the Viprinet project, which turned out to be much larger than everyone expected.
Jens Schönfeld