Thinner beam:
- more flex
- more dynamic behavior/response:
- higher (predictable) depth and spin control
- more balanced workload between racquet body and strings upon impact
- more, easier spin
- less ball speed in compact and medium strokes
- higher feel on hard swings, lower on slow ones
- less forgiveness in compact strokes (ex. volleys)
Thicker beam:
- less flex
- less dynamic response
- lower depth and spin control
- more workload to the string and hand/handle, less to the racquet body work
- less spin
- more ball (strait) speed
- lower feel on hard swings, higher on compact ones
- higher forgiveness in compact strokes
I don't think I can agree with this here, and it seems to be written in favor of thin beams, seeing as how better feel and forgiveness is only given to thicker beams on compact swings.
I spent the vast majority of my time playing with rackets that have thin beams and/or small heads and usually 12oz +. I also have APDGT and a crazy thick Wilson Profile.
I really think thin vs thick beam does not matter so much in general, rather its the characteristics of the individual frame that matters more.
I'll use my own frames and my own observations of them for example:
Frame 1: Volkl PB10 Mid, 93sq head, 19mm beam, has medium spin, a somewhat flat shot trajectory, less forgiving than Aeropro Drive regardless of shot type, more forgiving than frame 2 despite smaller headsize and thinner beam.
Frame 2: 98sq in, 19mm throat 22mm Hoop, has a thicker hoop beam but has very low spin, an even flatter shot trajectory, and IMO better feel than the Volkl. Of all my rackets, this racket demands me to be at my best to play well with it, even though it has a medium beam thickness and large head size.
Frame 3: Aeropro Drive GT, 23-26-24mm beam, high spin, good forgiveness on any stroke, medium curve shot trajectory
Frame 4: 95sq in, 22mm straight beam, high spin, less feel than Aeropro Drive, but everything else is extremely similar to APDGT to the point where I can freely switch between them, despite the headsize and beam width difference, medium curve shot trajectory
Frame 5: Wilson Profile, thickest part of beam is around 38mm, low spin, extremely flat shot trajectory
Frame 6: Boris Becket DC London (demo): 20mm beam, extremely high topspin, high shot trajectory/curve, firm yet flexible
Frame 7: 90 sq in, 20mm beam, medium spin, medium curve shot trajectory, extremely unforgiving on any shot, many people have commented on how harsh this frame feels after using it.
Frame 8: Yonex VCore 100s (demo), 24.5mm-23mm beam, felt higher powered than APDGT, very flat shot trajectory (a friend tried it and said the same, many of his shots that would normally clear the net by a foot hit the top of the net), stiffer, harsher feel than APDGT.
(BTW Feel free to disagree with anything I wrote about my personal observations of the frames above, ppl can never seem to agree much regarding rackets anyways as there is so much personal input from the user. Its just there as an example to show that beam width and frame/playing characteristics did not stay consistent for me.) From what I have observed, the characteristics of frames are kind of all over the place. Two rackets with extremely similar specs and beam width can play and feel very differently from each other and does not guarantee any kind of characteristics. You just have to try a frame out to see for yourself. Specs can be very misleading.