I wouldn't delid any processor. I think the gains are not too much, especially when you void the warranty and risk permanently damaging the chip.
The gains can be huge on some CPU's, on skylake for example, removing the IHS is a must to remain competetive in the world of extreme OC, my chip for example reached 5.9GHz under LN2 and after the delid 6.4GHz was attainable which is a huge difference. Although on ambient its not really worth it, maybe seeing a 100hz increase in cpu speed.
Some Haswell CPU's were worth doing, with a temp drop of around 18c (ambient) if Liquid metal was used and this may of helped some cpu's go up a couple of multi's.
Yes theres a risk involved but not so much with the delid tool but the gains can be very good and totally worth it, a cheap way (if it all goes ok of course!) of a cooler/faster system.