I would not change soft dome drivers if you already have them. Compression drivers would lead to increased efficiency and maybe more controlled directivity. But, the room is not large and these may be mute factors if you don't need them. Room consideration can't be underscored. That port is going to work out two ways. It will deliver a ton of air and hit you in the face with a lot of direct TR.. The other way is that is will keep port velocity low and the room won't have the wind tunnel effect but, will deliver a severe PR and indirect TR. Either way it should be great. Keep us updated with your progress. You may be into a new dimension of HT from what most of us are doing.
I have always liked soft domes and ribbons(planars) for music but always lacked dynamics for HT. MY M&K S-5000s were dynamic enough and sound great, but lacked a little detail and that big sound of some of the others. I was hoping the TLAH would combine the two. I remember when I compared the Triad in room gold LCR(old version), the S-5000, and the DR-200 and said the triad played a piano softest, M&K in the middle, and the DR-200 sound like someone was pressing the keys hard. Everything else about the DR-200 was better than the rest so I wanted that softer piano strike like the M&Ks.
I also remember when Archaea was comparing speakers and mentioned the LOTR:FOTR scene where the Hobbit knocked over the bucket of chains and fell to wake up the Goblins. He said the JTR sound like chains. I use that scene as well and my JTR 888LP did play that scene very nicely compared to the DR-200 which was harder sounding. The TLAH is the bridge between them IMHO. I am not sure on their absolute volume though. I am trying the brand new outlaw 7140 made by ATI. This amp is incredible with a zero noise floor with these 99 dB sensitive speakers.