As far as I know, the only solution for your A4000 to add extra Fast RAM, would be a CyberStorm 060. I've not seen a 030 or even a 040 accelerator (I had a Blizzard 4030 once) which you can fit RAM modules. Correct me if I'm wrong.
This is what I've heard, so take it with a couple of grains of salt...
Jens really dislikes the hardware design on these cards. According to Amiga lore it's Jens who today holds the license rights to Apollo. Owners speak warmly of these cards. Were the little brother back in the day of Phase5 cards.
Sucky SCSI implementation that only support FFS booting. RAM used to be expensive but is cheaper now. about $30 for 32MB Ram, not bad today for old RAM.
Very compatible with A3000. Overall good.
Excellent card. DCE cards use a poor BGA soldering technique on the 68k CPU which is prone to fail. WideSCSI can be cumbersome to set up on this card if you want to mix with narrow devices. Can have issues in A3000.