Hi Luke,
i didn't buy pc3k express as looked too much as a normal UDMA with more channels and higher price .... so i can compare only with UDMA, my pc3k is 5.6.6 ( i think should be the latest

).
Had they not giving you a unit to test, would you choose to buy their unit over an updated PC3K UDMAe or PC3K Express?
yes i received a test set for 1 month and then i bought it, about the purchase you said right "updated PC3K" ... actually i'm more confident on this new tool as it's a newer technology than Ace's and i already received 2 updates (as beta) with good improvements.
I liked the policy of free updates and the fact that they listened at me for wishlists, actually the support is good and fast but i understand that they are quite new so i not possible to judge.
Does it have all the power of PC3K? When you are comparing to PC3K, which version of PC3K are you comparing?
Is hard to compare as they are different and sometimes is better sometimes less i try to clarify, i like a lot the cloner utility as is fast even to create the sector maps for unread or error sectors i have to say that is more like a DDI 4 than PC3K DE.
About firmware utilities has some features i like, i think WD royl support is better:
through support they could rebuild ROM modules on drives with overlays mod "NOT INIT"
the speed on tracks reading is great (very much faster than PC3K), speed apart the other options are more or like like Ace's.
They lack a bit on head map in RAM for newer families, sometimes it didn't work.
About Seagate i could work with a good list of system files (also volumes not yet managed by pc3k

) 3 months ago and i could work on Lombard drives (the 4tb with no com port full access .. they opened it), on the other side here also they lack for head map editing.
as i told you i'm confident about updates.
Also, is the PCIe card a custom build or just a generic card, as it looks like from the photo on their website?
i think is quite difficult to me to tell you ... i can see that before windows booting there's an output with the name of the controller (something like "EDR Tool controller...") but i think is better to ask them about.
I'm sorry if i wrote such a long post but i hope this answered your questions

let me know