I have one.
And I've traveled in South India with it. If you are interested you can read about it here.
It has some bicycle and trailer review there.
yes, we were using trailer for that 3 month trip. But I can asure you that it would handle any type of fully-maximum-mega loaded tour. Dont know how badly loaded it can be for you, but once it is on the tandem, tandem will cope with it.
Ride is slightly diferent with those 20 inch wheels, but its a matter of short time till you get used. Mostly diference is related to the tandem steering - its more sensitive (or responsive). Otherwise it is more or less the same. Speed issue is quite subjective, coz i find it more depends on the type of tires you choose, rather than the wheel size, if to compare it.
Twitchines was not anoying for us, rather we enjoyed it. It is almost unnoticable, but it makes the ride smoother. but again, it up to your preference. It does not affect handling at all.
Optional drag brake - i have mixed feelings about it. We have it, but only for super high descends you might need it. Coz we were descending some 7 km downhills in India and those V-brakes were coping very fine. But yes, if you will have it - in Alps it could be useful.
Packing - probably better than "whole" tandem. But if you having direct flight, even with your "normal" tandem it shouldnt be to complicating, considering that you will need to pack and handle you BF anyway .
And BF VS S&S Couplers, i find Bike Friday tandem bit cheaper at the end.
One more advice - the tandem Q option is not worth the money. its my oppinion. Simply because its so complicated to convert, that even puts you off from converting.