Many variables to consider and generalize. Ceteris Paribus, generally I've found the oversize frames give the boost in spin generation (being more open, steeper contact angle), and if lighter, racquet head speed which results in slight boost of power, assisted by the longer strings.
Extended racquets increase swing weight and very minor increase in height of contact, for any given weight (for eg, EZ98 vs EZ98+), so there will be a noticeable boost in power, and probably a heavier ball. Funnily, I find Babolat's Plus line to be less pronounced to the standard length model. I tried the Aero and Aero Plus with the same strings, and the swing weight was only 13 pts, vs the usual 18-20 pts with Yonex. So it's not all the same.
Still physics rules, and stiffness is what gives the most power boost. I have been tinkering with an Angell TC100 27.5 70RA, specced up to my SV98+ SW,balance etc. With the same strings, I couldn't get the TC100 to match the speed of SV98+ on serve. Groundstrokes were closer in speed and spin. So it's not always about length and head size, but also stiffness. The Angell turns out to be 70RA without grommets and grip etc, and 21mm thick and 63RA, while the SV98+ is 68RA strung, and 22mm. Even with a tighter string pattern, my serves are Playsight proven to be"heavier" in both speed and spin.