"Mo bass,mo problems"(btw,my friend had the very fine Eclipse)...Well,from my experience with the REL Stentor/Avalon Ascent MK-II......Your assumption has merit!!....The Ascent is a rediculously sensitive speaker(a good thing in the long run).I have had it sounding about twenty different ways!!Literally!!....
I'm willing to bet(a penny-:)that those who sold it,"never" heard what it could do!...Especially with today's better componentry!!
Each time I thought the speaker was doing something,it turned out that it was some other parameter.....This has happened,like a zillion times!
Finally,I must conclude that this design is absolutely an electron micrscope on "whatever" is before it.So,when the speaker was originally introduced,some felt(including me)that it lacked the lowest freq(even though it got rave press)......It DID,but as time has told me,ONLY a TINY amount of low freq is absent....Time and technology allowed for some interesting sub bass systems to be considered.
I felt the speaker was underperforming(even though it sounded great) because as the other components got "that" much better,surprisingly, the speaker knew it too!!...Always!!...Time and time again!...An amazing design(460 lbs with crossovers...whew!).Serious!!-:)
Ok,but since I wanted to take advantage of the amazing stage proportions this design had(it smoked my big Infinity's...both the RS-1,and the Infinity Beta.... four tower designs),I moved it 7.5 feet out into the room,and boy this speaker "liked" that!!But,you are going to lose a bit of impact,especially with a sealed design in this scenario.
I waited a long time to "do" a sub,not wanting to screw things up.Very easy with any sub,because "everyone" gets hooked on "lots of bass" at first!!But I got it to blend seamlessly,after lots of careful consideration,and am thrilled!!
So,to answer the Eclipse question,....you can get deeper bass,with more weight/impact...But basically it depends on how you have the Eclipse set up.What you want in bass.I like just a hint of added weight/depth.I only use about 1 click stop of volume,on my sub.That's only 10 % of the gain available,but since the basic Ascent has proven itself after almost "any" change in set up variables(it's that sensitive,even at incredibly low volume levels in resolution),I realize the sub question means getting the sub set in an almost "exact ideal" room position,or else doom!...Tread carefully,but it can be done!
Btw,sorry to go on so much,though we are all basically talking "Avalon" products.
I would LOVE to hear the "Diamond" someday,and think it most likely a magnificent product,especially when one sees so much very expensive foreign competition.Not likely to better the "Diamonds" by much.Just an opinion.
Best