@lempkee - I'll scream at you later in IRC for that crack about "real amigans" (btw, this is 2th).
@Zadoc - Quite a well written reply! I concur with a lot of what you said, read on...
Now, I'll add my 2 cents - from the perspective of someone that already has quite a few Zorro based cards for his A3000D: My system's tanked up with a PicassoIV, Catweasel S-Class, Highway + Norway, and MultiFaceIII.
As Zadoc mentioned, there are a TON of benefits to using industry popular/industry standard PCI cards: Voodoo cards have hardware 3D acceleration & 4x more video ram than my PicassoIV. PCI IDE/ATA interfaces run rings around the Catweasel's IDE and there's even a PCI Catweasel that lacks IDE but gains a real SID chip. PCI USB 2.0 solutions, and probably highspeed serial/parallel PCI cards. The list goes on...
However, there's the matter of whether it'd be worth it, in light of the Pegasos/AmigaOne upgrade paths which I'm CERTAIN would be many times faster. So there's the cost factor: upgrade the legacy hardware with this and extend it's life (get further behind the new stuff - depending on how you look at it), or evolve to the next gen hardware for a few hundred more.
Then there's the question of Elbox's integrity. They've handled themselves VERY poorly in relation to the P96 issue, and more recently when they were called out on their RDB trojan (for the record, the original poster stated he was a registered owner of Elbox products - so don't cry to me about "Oh, they were OBVIOUSLY pirates"). Their behavior on hardware support mailing lists also leaves a LOT to be desired.
BTW, as lempkee can attest, crying to me about how much they've done for the platform will fall on deaf ears. It is a piss-poor EXCUSE for their conduct and it doesn't cut it. Sh*t served on fancy dinnerware is still sh*t. So don't bother preaching to me about Elbox in any replies that follow.
These would be the two main reasons I wouldn't recommend getting a Mediator.
The Mirage tower solution, though "tiny" for what I'd need (it needs more 5.25" drive bays), has been the ONLY product Elbox offered that I'd be willing to set my principles aside to purchase. If it came in a full size tower, it'd certainly tempt me even moreso, since the limitations of the A3000D's overall design is a real pain (only 4 Zorro slots?! And what were they smoking when they thought up the case?!).
Remember, this is merely my take on the situation, since I already have a bunch of Zorro equivalents. If you lack the hardware (say, a bare A3k, 1200, etc), it might be worth considering if you don't want to make the leap to the nextgen machines. For me, I'd have a real problem justifying the cost (even if I considered the hassle of selling the Zorro cards, which I'd never do anyway), though lately the PicassoIV's been pissing me off with the way it handles it's video ram.
One last thing, you may also want to consider the Prometheus, especially in light of the fact Matay now has the capability of upgrading their cards to enable DMA (which I understand was a big downside of their PCI solution). Perhaps redrumloa could elaborate on this? I'd certainly appreciate the info.