Since +P ammo has more recoil, and it's best to train with the same recoil that you will be shooting with in a defensive situation, I'm guessing not using +P at all is the best philosophy?

I wouldn't want to train with +P because it is more expensive and hard on the gun.

Train with what you carry. +P is not "hard on the gun".

Yes... it is more expensive.

I have shot +P+ exclusively and issued 100s of thousands of rounds and it was never detrimental on any brand of pistol shooting +P+.

Good idea shoot what you carry.  You don't have to shoot a ton of it and break the bank.  I have shot carry defensive ammo and fmj range ammo.  They shot to different points of aim due to velocity mainly I think.  Just know how your carry ammo shoots. Just my thoughts.

It's hard on the gun if it's a crap gun.  Not if it's a decent modern pistol.

Train with what you carry.  One of the many reasons reloading is such an asset....you can duplicate POI and recoil impulse of a hot defensive load for pennies.

Most decent quality factory FMJ is pretty close to carry ammo recoil.  If you have time on the range shooting and learn how to shoot your gun, the amount of recoil it will have, as well as differences in felt recoil, should be a non-factor to your performance.  
That said, +P ammo is not needed in general unless you want a specific ammo that is +P.  Most bullets made today are designed to penetrate and expand at lower velocities than previously designs.