If you are after 1.5 inch of gain on each side,the 4+3 wheels are probably better than spacers.The bearings won't know the difference between spacers and stock wheels or 4+3 offset.I went with 5+2 wheels and 1 inch spacers so that I would have options on width.
agree if going wider it makes no difference as the forces are the same regardless of how you get there. And given the small amount of width you are adding, the low weight of the P500, and the low weight of the tires/wheels you will make no impact to bearing life. If adding 6" to each side and adding much larger and heavier/tires wheels then yes. How many of us run larger tires and wider offset wheels on cars and trucks for thousands of miles with no impact.
Only caveat is that if running spacers/stockish wheels, you can remove the spaces and hit the odd 50" trail now and again. If you don't run 50" trails, then i agree...simple is better: Just do offset wheels.