For what it's worth I have experimented a lot with racket head size for my single handed backhand and here is the story of my evolution.
I started out with the Wilson 6.4 power holes OS, stayed with it for a couple of years but never really got my backhand going with it. The advantage was that I could hit a godd topspin backhand on a short high ball, always had trouble on deep balls or hard flat. The biggest problem was what's called the "trampoline effect" -in short the bigger head size combined with low string tension creates a very bouncy sling shot like hit as opposed to a crisp hit from a high tension stringing and a stiff frame. The problem with the trampoline effect is the lack of control when trying to hit flat or when returning a hard hit, such as a flat serve. As I moved from 3.5 to 4.0 my opponants were able to hit harder and I didn't have enough time to hit a looping tospin backhand on every shot. The 6.4 was a disaster when I tried to hit flat with a shortened swing, the trampoline effect just sprayed the ball all over the place. Besides that the slice backhand tends to sit up as well.
With these issues starting to become a factor I started demoing rackets during which I discovered the Dunlop MW 200G 95" and immediately fell in love with it. It was great for the backhand, I could hit the loopy top spins as well as flat when the situation required, the slice was also starting to stay low. The only thing I lost was a bit of bite on the topspin. With the 6.4 OS the topspin was an offensive weapon, with the 200G it became more of a rally stroke, but the consistency across various backhand strokes was great.
Well as things would have it, I started discovering that there were other parts of my game which started suffering because of the racket (mainly the semi-western forehand) so the demo process started again. Being aware of what the trampoline effect could do to my BH I was staying away from OS rackets and started looking into heads in the 98-102 range, hoping that this would provide a good compromise between the various strokes. This is when I discovered the Volkl C-10 pro. The feel is very similar to the 200G, but there are distinct advantages. The head size is slightly bigger, which combined with a more open string pattern brought back the zip in my topspin BH. But the trampoline effect was absent so I could still hit flat when needed. The slice was equally good. I think the C10 provides the best compromise between the three main BH shots; topspin, flat and slice. So I have been using the C-10 for the last 3+ years, I have demoed several other rackets (usually following a loss in a high stakes match) during this period, but keep coming back to the C10.
Coincedentally during this period I tested the Prokennex 5-G OS. It only came in 28" length and had a tremendous swing wt. so I cut off 1" from it's handle. This standard length PK 5G is probably the best OS for backhands among the rackets I have tested, and I have demoed between 20-30 in the last 3-4 yrs. If I had to go to an OS this would be my first choice. The reason, I think, the PK 5G doesn't have the trampoline effect is it's stiffness combined with the kinetic mass. I have demoed the POG OS as well, a good racket in itself, but the PK-5G standard length kicks it's ass in every aspect. Have not tried the C-10pro OS, about which I have heard good things, but that too is extended length which usually spells disaster for single handed BH.
A long term observation I have noticed about my game is that in general since switching to midplus head my BH technique has improved quite a bit, I think the heavy weight of my racket (I add about 5+5 grams to the frame and handle) also plays a part. But gradually over a period of time I have automatically gotten into a habbit of early preparation, which does wonders for you SH BH as it depends highly on timing.
I would suggest you try something in the midplus range with a weight over 11.5oz. Unfortunately the demo from a pro shop or TWH is usually limited to a week max. but you need to stay with you racket for 15-20 sessions to give your muscles enough practice/memory to start adjusting to the differences in swing weight. Once you get you timing right on a heavy racket with midplus head you wouldn't think OS any more.
Just my 2C
Volklalite.
