Drain damage has never been able to be healed in previous editions, so why should that change now?
Healing rules are completely different with 6e, which is why I said may, not will.
Ah, yeah that's not how that 'may' came across, it came across as 'with X changed, the following tactic may become interesting', not as 'maybe X changed and will make the following tactic interesting'.
From what I understand to take no drain from a summon requires 3 times as many hits as the spirit has
That sounds overly dramatic. They'll be the same drain, you just can't edge it as easily due to the remake of the Edge system. And the drain will in fact be a more narrow bellcurve, due to smaller standard deviation with rolling Fx2d6 instead of (Fd6)x2. The main complications will be that it's harder to get services and that the drain will be harder to Edge against when it rolls exceptionally well. But that just serves to encourage people not to throw in massive-Force summons, so no harm done.
At 13 drain dice, a Force 4 will average 0.26 drain and a Force 6 will average 0.77 drain, with odds of 4+ drain being 5%. So a single hour nap would suffice even if a Force 6 is a pain, and several Force 4 you won't really care about.
I am concerned about Strength as a stat. Only applies to Unarmed combat for damage, no longer provides to melee weapon damage? Did strength just become a dump stat?
To me, Strength always was a dump stat. Shock weapons sufficed, even if I had to grab Indomitable to up my Physical Limit.