I am on the same trip and discovered a barely crunchy Tubescreamer into a Rat. Now i look for DIY clones at pedalpcb.com and aionfx.com into a double sized enclosure. Will be a fun project.I've been on the hunt for the 'end all be all' distortion pedal for my board, and I think this is it for me. After going through countless other gain pedals and OD combos, I decided to give this one a shot and am pretty pleased with it. It's got a useable function pretty much any way you set it, depending on your rig of course. I particularly like it with the distortion set to about 2 o'clock, Filter at 9, and level to taste. Plus it stacks well, which is always a plus. For the price, Proco Rat 2 hard to beat!
For how a TS into Rat sounds look here at the end (12:50 min) playing with a TS10 into SK10 (Rat clone)