Ok- I agree it's all listener preference, but -my preference- is the inside. It enhances image sharpness. Outside tweeters provide a wider soundstage which isn't necessary for my room and me, where the inside tweeter positioning gives a sharper and more delineated image which to me is necessary.
To me there is no comparison.
The 20.1 is a far superior speaker to the 3.6, I owned the 3.6 and the 20.1 beat it up and stole its lunch money. I upgraded.
If you like bass, buy the larger speaker. If you like to mess with things, buy subs and try to integrate them. More trouble than I wanted, so I gave up.
I have Wotans on 20.1 and I think they are sublime. If you had the cash, VTL will still build you a pair at last asking, but the new smart tube technology has made demand for Wotan lessen. At this point they'd be as expensive as a tiny house, or a down payment on a larger one (at least 60k I'd imagine).
Should the audiophile community ever realize what fine amplifiers they STILL are, and how truly well they do on speakers that cannot be biamped (Magnepan owners, Soundlab people, Wilson and JM Labs customers, are you paying attention??) perhaps Wotans will increase in value or perhaps they will release a Wotan II with the Smart Tube technology. I will hang onto mine. Zero problems, besides tube failure and the resultant blown fuses. (There is a trick to finding out which tube blew, but I've yet to use it, it always seemed to be a good excuse to test all the tubes and bias the amps again.)