I too have an AA130.
I haven't used any PEX...YET...but, I intend to as I expand my system sometime soon.
It is not so uncommon for my AA130 to pump water at temps above 200* due to overshoots, and that is a concern w/ PEX.
As I have been accumulating parts for this future endeavor, I did picked up a couple thermostatic mixing valves for cheap and will plumb them in to tame any temp spikes.
And besides myself, I know *AA130Fireman* uses a Air to Water heat exchanger Coil in a forced air systems.