We're converting from PF/3X to 5E. Have run 3 major multi-day sessions since the Starter Set came out.
Now, we're going to continue our Shackled City campaign.
House rules... We're in the process of converting some classes and feats from 3.x, PF, and Arcana Evolved (especially the giant race/class).
Also, using a lot of 3X/PF monsters (mostly just adjusting AC and Base Attack to 5E levels).
Also, allowing some 3X/PF spells and/or Warlock invocations.
Also, we're using the expanded weapon critical ranges of PF/3X (on the PC side, for now, but named NPCs will likely be able to use the expanded crit ranges, too).
Also, using the PF 25-point buy, instead of the 5E 27-point buy (about the equivalent of a 37-point buy in 5E).
You might want to check HP for any converted monsters as well. The 3x/PF version might be a little low.