I've been a London user since September. It's a great stick. I had been demoing racquets for about 3 months prior before I found the London. There were a few things that separated the London from the rest of the pack. The most noticable difference was the spin potential and the dwell time. I'm a 3.5 player top spin player and the the amount of spin this racquet created was incredible. Part of this was due to the dwell time and the other reason was the lightness of the racquet because I was able to maneuver the racquet and get on top of the ball on my swing. Also the maneuverability and the dwell time has improved my second serve as this racquet provides plenty of confidence to go for more on a second serve and still get it in.
I usually prefer flexibly heavy frames with thin beams. The London has the stability of the heavier racket and more power than other thin beamed players frames that I have demoed which makes it unique.
So far, I've tried Technifibre NRG 17 @ 53 lbs, Gamma TNT Fat Core 16 @ 56 lbs, and Chris of TW's setup of Cyclone at 52 lbs. I did not like the TNT Fat Core... The NRG and the Cyclone have both worked well for me with the NRG being a softer more comfortable string than the Cyclone, but the Cyclone has offered me some unreal amounts of spin. I think my next set up will be a hybrid of the two.
If there is one thing I'm experimenting with, its lead to see if I can make it even better. While the racquet stock is awesome, I prefer a stick that's a little heavier. My swing tends to wander and get loose when a racquet is too light and a heavier racquet allows me to keep a more consistent swing path. I tried Chris' TW setup with 8 grams at 2 and 10 and found it way to heavy for me. Next, I'll be experimenting with about 4-5 grams this week. It could be that stock is still the best set up. While my forehand may wander a bit due to the lighter weight, the racquet is still very stable and extremely forgiving on mishits.
Hope this helps those who are thinking about demoing this stick... I've tried other Becker racquets, and this was the only one I really bonded with. One other thing to note is the grip handle shape which is quite rectangular and can take some getting used to.... personally, I think it's worth adjusting to... but you should demo this racquet to see if it's worth it for you.