To those who commented on the C7s, I agree that the room, associated equipment, and setup make a huge difference. I only heard them once for a short duration, and it is quite possible that it was a one-off. I would love to audition it again, but unfortunately there's no way to do that right now.
Moving on to the HL5s, I think they might be too much given the room size and listening distance. They might work, but given that my ability to position them properly in the home office is rather limited, it's a risky proposition. 40.x is pretty much out of question -- I just don't see how they will fit my room, aesthetics, and most importantly my budget.
At this point, I'm leaning heavily in the direction of 30.1s. Would love to get 30.2 but I don't think I can find a used pair around $3k. From what I have gathered thus far, they retain the sonic qualities of P3esr but serve them in a bigger, fuller platter. Just what the good doctor ordered. These seem to be the goldilocks of the Harbeth lineup, at least for my specific requirements.
For now, this is what I plan to do. Try the P3esr's with my REL T/Zero in conjunction with Blackhawk's dedicated sub out. But eventually, and knowing myself, I would most likely give the 30.x a try.
Having said that, I wonder if there is another speaker that retains the sonic qualities of Harbeth but is tube-friendly. I rather like my Blackhawk and would like to keep it if at all possible. The problem is that I have never met an efficient speaker that I really liked. I have auditioned the Klipsch Heritage line (except LaScalas), Devore O/96, and a few standmount models from Proacs, but none has appealed to me like the Harbeths. I understand that these are amazing speaker, and I don't intend to offend the owners, but just not my cup of tea. If someone can suggest non-horn speakers that are efficient and have a similar sound signature to Harbeth, I'm all ears.