Less heat? yes
Less eye strain? Definitely no
Less warping? Maybe. I have seen plenty of old NOS playfields with cupped/raised inserts. I am convinced that has nothing to do with the lamps and more to do with the wood expanding and shrinking over time with humidity, etc.
Fact is LEDs were not meant for older machines. Square peg meet round hole. Strobing and flicker causes eyestrain and headaches. Also, makes the ball harder to follow. I buy one of your monstrosity complete LED machines and I don't even turn it on when I get it home until all of the LEDs are out and real bulbs are in.
New games like ACDC LE/Premium and XMen LE have completely redesigned circuitry meant from day one for LEDs. No problems there - round peg in round hole.
John