I'm using EIDE99 with vamp in my A2000. Works fine with AllegroCDFS.  Speed seems acceptable. Haven't run any benchmark yet. Trying to solve  why Xsurf100 refuses to work. But I don't think it has anything to do  with EIDE.
Very useful to know!!  I was thinking about getting one so that I can remove my scsi card. 
As for Xsurf100.  I have my A2065 working with vampire so at least in theory an ethernet solution can work.  note:  I am using AmiTCP.  There was some work be done to make a Ethernet adapter for the microSD slot.  At least on youtube you can see it work, but not have seen anyone selling the adapters.  This might be a long term good solution in lieu of the Xsurf.
Additional cards I have tested, A2386, IVS Trumpcard pro, and A2058 with without any problems.  I have not tested any of the more exotic cards.