I had 11s with a wound-third on my HB Spruce up until recently. I just switched over to 10s, with unwound third.
The sound is different, but not drastic enough to say "OMG, what were you thinking!" (the 10s make it less punchy sounding when you strum harder, and the overall signal output is 10% lower or so, in my estimation).
I had no problem playing with the wound third, and could bend up a full step or beyond if I needed. I just wanted to try out the 10s because I had found the signal output of the piezo at full volume to be occasionally "overdriving" the acoustic simulator pedal I was using, even with an EQ pedal in front to tame it. Putting on 10s has mellowed out the sound a bit, and makes it a bit easier to play, overall. I generally have 10s on all my other guitars, either regular 10s or hybrid 10s (light tops, heavy bottoms), so I was OK either way with 10s or 11s on the HB.
PRS ships the piezo HBs (which is al of them, now, AFAIK) with 11s because it produces the most acoustic-sounding signal straight out of the guitar into a PA, so if you do nothing else to the signal it is the preferred way to go.
But if you plug into a regular electric guitar amp, or use enhancements (
) such as additional acoustic-simulator pedals like I do, then 10s are probably fine. The wound-third certainly adds a touch more acoustic tone, but as noted, your audience won't notice.
IMHO, YMMV, etc.