I can't comment on the VA HGs as I've never heard them, but I do currently have a pair of both the Sierras and D2.1 SEs. Note that right now, I only have the original, stock versions of each and don't yet have the new upgrades that are now or will soon be available for the both of them. I haven't ever really direct A/B compared them to each other when level matched, but I've listened to one for an extended period of time, then the other for a while on the same electronics in the same room though.
They definitely sound very different from each other. It has been covered in depth here and at other forums about the differences between the two, of which I really can't add anything new to that hasn't already been said before. IMO, the Ascends definitely make the bigger first impression right off the bat, but as time goes by, the tables start to turn (at least they did for me). The more you listen to them, the more you start to appreciate just how damned good
the Swans really are. They just kept drawing me in more and more over time. The more time I spent with them, the more and more I liked them. You can literally listen to them both all day long without ever getting listener's fatigue.
As for some intangibles, I think the Swans look much better (mine are gloss piano black for the Swans and the natural bamboo finish for the Sierras). Also, the Sierras have optional port plugs which help to give them much more flexibility in placement and set up options however, whereas the D2.1 SEs pretty much HAVE to be on stands out away from the front wall behind them. So if you are unable to place them this way, then your decision has already pretty much been made for you by sheer default unless you were willing to maybe consider the Swan D1.1 SEs. Another thing is that if you were to do up a surround system with them (I only have two channel for them both right now), it looks to me like the Swan's D 1.1 SEC matching center speaker might be a little better than the Sierra1 Center, but I'm just speculating here. Also, I think I saw something somewhere that there might be a forthcoming D2.1 SEC, which should be even that much better than the current model. Maybe Jon can confirm or deny this either way. Speaking of which, BTW, both Dave and Jon are extremely helpful and knowledgeable, and you will great, top notch, 2nd to none customer service either way.
The final intangible is the Swan is usually somewhat cheaper, thus arguably a better value. Note that I got my D2.1 SEs when they were on sale for $500, plus a set of their matching stands for $99. Shipping for the speakers and stands was $74 and some change, so figure the total cost was right at $675. I got my Sierra1s "re-certified" for $678 with free shipping. So basically I got a free set of stands with the Swans that they look good on (whereas I've never been truly happy with the way the Sierras looked on any set of stands I've had them on because of the natural bamboo finish). Plus, the Swans were brand new while the Sierras technically were not.
The Sierra1 obviously has a big following here at AVS, which is definitely understandable and justifiable, but I just can't understand why the D2.1 SE doesn't seem to have a bigger following here than it does. Especially when it's usually a little cheaper than the Sierras, thus arguably a better value. They are both IMO excellent speakers at their price points which compete very favorably with anything at or even double their price, either ID or B&M. I once bought a pair of Revel Performa M22s new in the discontinued maple and black finish on clearance for half price of $1000, but short of stumbling across a deal like that, it would be hard to top them in a new speaker for the $$$.
Bottom line, like I said before, the Sierra is also a great speaker too, but if forced at gunpoint to choose one or the other, it would be the Swans. But if forced at gunpoint to give up the Swans, I'd be happy to keep the Sierras (and live). Now, that is all based on the current, stock models. It may very well change after I hear the upgrades.
My advice is to wait to the new upgraded Sierra NrTs are available, and order a pair of them, and also order a pair of the new upgraded D2.1 SE Customs at the same time. Spend a month listening to them both in your
room with your
music/movies on your
electronics and decide for yourself which you
like better. Then return the one you don't like as much for a refund. IMO, it would be well worth the cost of return shipping for one of the pairs to know for sure for yourself exactly which one you like the best instead of always have that lingering, nagging feeling of wondering "what if".
Either way, whichever one you pick however, you will have a great speaker! It's like being able to have a choice between Angelina Jolie and Charlize Theron, you literally can't lose no matter which way you go between them. Although having them both at the same time would be the bomb!
Again, I would HIGHLY recommend auditioning them both for yourself to make your choice instead of just taking the word of me and/or others.
Hope this helps.