I've had 4 BMWs and sold my 1150GS and later bought an F650GS. I've had it for 3 years now (just off warranty) but have not put tons of miles on it for a variety of reasons. I did put lots of miles on my 1150 including a run to Guatemala from Colorado.
The F650 is one of the nicest rides I've ever had - a bit underpowered on the highway but certainly acceptable. As a commuter it's a superb ride. I've probably spent $2.5k on farkles including rebuilding the seat, new windshield, engine guards, etc. but I could see spending that on the Wee as well.
I love the F650 - when it's running right and there's the rub. BMW completely blew it on the fuel system set up and I've had the bike in at least 4 times for new injectors, fuel pump, cracked fuel tank and it still has some problems they do not seem to be able to work out with the engine dying when down shifing from time to time. Unfortunately I no longer trust the bike and the worst thing that can happen with a bike is to lose trust in it. Two or three times I've looked at Wees and should have pulled the trigger on a great deal last fall but was hesitant for a day and lost it. I hesitated because I just have too much money in the F650 and I really want it to work. I'm going to ride it this summer and if I can cure it's problems and regain trust I'll keep it, if not I'll probably pick up a Wee or look for an old 1150GS again or maybe a Moto Guzzi.
I feel the Wee is a much less sophisticated bike and that's exactly why I'd buy it - the F650 and all the recent BMWs seem to be way over-engineered to the point of being somewhat fragile - they have a really hard time handling something as simple as 10% ethanol gas and are, at least for me, fairly difficult to work on. As for being boring, I've never been bored on a bike, even when crossing the plains or on other long runs with minimal external stimulation. I have, however, been really pissed when my F650 stalled and kept stalling and I have been bored when my bike was in the shop for weeks at a time while they replaced injectors and parts that could not handle the most common gas mix in North America. Just my experience, yous may vary completely.