It would be very interesting to know if the principle of 'subrogation', as is heavily larded on one broker's website, has ever been used against a renter and under what circumstances. As far as the deductible is concerned in my view that's an acceptable risk in the grand scheme of flying.
The company I work for doesn't write a whole lot of flight school policies due to the obvious reason of high exposure vs. little premium(Joe PPL propstrikes a C-172 which wipes out the premium for 2 years, but then Shmoe PPL does it again the next year) but I can say subrogation can be pursued pretty fiercely by the insurance company. The more money involved, the more they'll go after it. For instance, a helicopter total loss causing the insurance company 1 mil dollars is a tough pill to swallow, so if there was some circumstance that caused the accident- failed part, bad maintenance, and it can be (sort of) proven, they'll go after the guilty party to recoup some money. They never get all of the money back, 50% return would not be a terrible outcome after all the attorneys are paid.
On a smaller scale, if Joe PPL is clearly at fault in an accident, subrogation is likely. The key to is it all is- can Joe PPL and his insurance company mount a reasonable defense? On the little stuff(physical damage) adjuster A might subrogate against adjuster B and they work some kind of split. Aviation claims is a small world and what goes around comes around, so we take that into consideration. If Joe PPL kills somebody and damages are in the hundreds of thousands, subro is very likely and the lawyers come out.
Again I don't see many renter's insurance claims, but I have seen small maintenance shops be subrogated against due to bad maintenance and if they didn't have insurance guess what? They paid out of their own pockets, and that's tough to witness. Moral of the story is that it doesn't hurt to have a decent insurance policy, renter or flying club, because when the sh!t hits the fan, you'll thank yourself for it.