I'll add my $0.02 here, as I recently used my first Archer chain. I read some of this thread before I bought this chain, so maybe it's fitting that I comment here.
I'm impressed. This was brand new chain, on a nearly new bar. I think I made 3 cross-cuts with the bar prior to this exercise.
Here's the setup:
Husqvarna 2100xp with base gasket delete and a modded jungle muffler. I'm running a 42" Oregon with a Stihl adapter, 3/8-.063", and like I said above, that bar has very little run time. Not running an aux oiler.
The chain was fresh out of a sealed Archer bag and I tightened the chain like I would have done for any chain. Not overly tight, not loose.
I had a usable milling width of 34" and used it all in about 5 cuts, with another 5 being about 25" width. Cut length was roughly 48". Wood was green, silver maple. (I know it's not a terribly hard wood).
The chain didn't "stretch" at all that I could tell. It's still all bolted up to the Granberg and doesn't appear to need any touch-up or tightening.
Take my experience for what it's worth: I'm not a wood worker, and I'm a bit of a novice at milling of any sort. I've managed to cut a few dozen planks/slabs over the past 5-7 years, and sometimes I actually follow-through and make something from the milled stuff. haha.
Any of the irregularities that I got in my lumber finish I can attribute to my technique, pausing or hanging up on the undulations on the log, or simply not getting the wedges in the right spot when I finish the cut.
My limited experience usually gives me 'some' stretch after cutting even on chain that's broken-in. Maybe I just got it more solidly loaded against the tensioner than I normally would, but I have no sag at all after running about 3 tanks of fuel with no re-tension or re-sharpen.
Your mileage may vary.
Phill