I wrote a post yesterday then deleted it because I thought you were referencing the small log mill. Unnecessary name changes causing unnecessary confusion, lol.
Anyways, I found the 372 to be fairly cantankerous on the edging mill. Half the time, even in the cut, if I took both hands off the mill, it would want to tip. So if something moves or you need to move, it's safest but a hassle to lift the whole jig out.
On a couple cuts, I had to use the 390 with the edger. It was even more unstable and awkward than with the 372. Part of it could be I still had the full wrap on it, so the balance wasn't even.
I was largely working on slopes and somewhat unstable ground, so any little change in my body stance could make the mill wiggle.
A smaller, more compact powerhead is ideal with the edigng-mill. For fun, I made one cut with a 353 on the edger, and it rode way better and was barely prone to moving or tipping when idling hands-free.
