I have a Savage B-Mag in 17 WSM, but have not yet gotten game in front of it. Based on reactive targets (oranges, water bottles, jello blocks), it's clear that it's a step above the 17HMR, but not to the 17 Ackley Hornet (or Fireball, Remington) level.

I suppose it depends what you consider to be "too much for squirrels." For headshots, I can't imagine that it's going to do significantly more damage than a 22WMR Vmax or 17HMR, and certainly won't do any additional meat damage. For body shots, it'll do more damage than an HMR, but unless you're a much more fastidious squirrel butcher than I am, I don't anticipate that you'll see much difference in what makes it to the table. I don't believe, in shooting "cuties" (small oranges) with the 17WSM and HMR side by side, I just don't expect that squirrels will have enough body mass to create too much more expansion - in other words, if your experience with the HMR has been like mine on squirrels, you won't see the WSM blow them to pink mist. My experience with the HMR has been that if you hit the shoulders, it ruins a lot of meat - as will the 17WSM.

Hit a squirrel in the belly button with either, or in the eye, you'll have just as much meat available with either.