In Part 2 of The Swing Out (Swing down) gate, David combined Peco track with an Atlas re-railer section. He didn't make a comment on issues combining the two brands. As Peco tie heights (thickness) is different, was there anything special he did?
Co-owner of the proposed CT River Valley RR (HO scale) http://home.comcast.net/~docinct/CTRiverValleyRR/
I mix Atlas and Peco on the Code 100 portion of my layout. I soldered the rail joints together so the rail heads are flush. I use foam roadbed, which compresses enough to take up the difference in overall track height, tie to railhead.
The other issue, at least in Code 100, is the rail joiners. They're just not compatable at all, so you'll have to get the larger one and squeeze one side. Again, soldering the rails keeps this from being a problem.
It takes an iron man to play with a toy iron horse.