A non-+P-rated airweight
should be ok with occasional use of +P. For example, fire a cylinder or two to check for reliability, how it shoots, and whether or not you can handle it, then maybe periodically fire a cylinder's worth to keep up. It will accelerate wear, which can affect timing, but you're not likely to experience a catastrophic failure ("not likely" is not the same as "never").
However, as has been said, there are a number of viable self defense loads that are not +P (presuming you can find them...

). My favorite is the Federal 125gr Nyclad, though that's been discontinued for a while now. I still have a few boxes on hand. I've been wanting to try Winchester's 130gr Defend JHP load. 148gr wadcutters are another good option. Though I use +P in my 642-1 (which is +P-rated), I keep some WC on hand as a low recoil option.
I will give a little cautionary remark. Buffalo Bore makes some loads that they say are standard pressure, i.e. not +P. However, because of the velocities they're able to produce, I consider them the same as +P and use them accordingly.
Just my opinion.