As the recent owner of both these fine frames, Head and Wilson have really improved racquets in this weight category. I will describe the differences between the two. Both of these racquets are better than the Head Graphene Prestige Pro, also at 11.1 oz
They are stiff at 66 (Pro Staff) and 67 (Speed), penetrate the court faster and drive the ball straighter. But the feel is not tinny as a Babolat Aero Pro Drive or Pure Drive due to the thinner beam, in the middle at 21.5 mm (Pro Staff) and 22.5 mm (Speed). The beam is neither traditional box beam of older Wilson frames or rounded hollow tubular beams of Babolat yore. There is a blend of the two beam designs which yield the feel of thin box beams with some of the stiffness of Babolat make.
The Pro Staff 97 is the lighter version of the current Federer model, the RF 97. I really enjoyed the maneuverability of the 7 pts HL balance. It actually felt as maneuverable as any serve and volley stick. But this is no flimsy stick on the groundies. I took as wide a modern swing with this stick, rotating the shoulders closed and closing the face, throwing all my weight into the rally shot. The Pro Staff delivered with great diving drive shots to the corners with minimal flex in the hoop. I was amazed at how much straighter the shot was but with all the action of a forward spin dipper. Serves had great kick and the flat serves had extra zip. Volleys were saber like. I did have to lead the frame at 10 and 2 o'clock and put in a stiff string, the new Head Hawk 16 gauge to maximize the effect. There were hot spots on the backhand slice without the lead, but with lead, I got the plow I needed.
I still felt there was a little room for improvement and looking at the beefier specs of the new Head Speed Pro XT, I bought the racquet without a demo. I was not dismayed in the least. The hoop was stiffer, the beam was wider, and the head size wider. I served even better flat serves with this stick than the leaded RF 97. I saw no need to lead this frame as it was belting every ball even more, as I hooked my forehands and backhands even more radically with my wrist. The flatter volleys stayed remarkably lower and the high forehands I could club straight out of the air with vengeance. The feeling is more Ferrari like as you feel the ball spit out of the stringbed like a rifle. Whereas the Pro Staff required a touch more work for the same result, the 18x20 pattern made down the line shot deadly off both wings.
I will keep the Pro Staff 97 for doubles and lower level scenarios. But the new Speed Pro XT is my choice for heavy duty singles mauler sessions.