Well, a week later with it. It's solidly tied with my 510s. It doesn't produce more vapor or throat hit, but:
1. I still like auto batteries..I can run to the mailbox, or go work in the yard, and hang the M201 from my mouth, even if it's got thee whistle-tip.
2. Battery life is at least 50% greater than the 510.
3. Cart capacity is good. It doesn't drain the full cart, but a cart will outlast the 510, starting from fresh blanks for each.
4. Consistency remains good (as it does with the 510s as well).
The M201 is on the large side for going out with - work, lunch, dinner, bar, etc...
It doesn't produce the throat hit the 510 does, but it's quite acceptable with some juices, and vapor production is solid.
No additional negatives found - all attys and batteries going strong (I do not drip auto battery ecigs). Waiting on my 801 from ruyandirect, am hoping a manual 801 battery will work on the M201, or a PT (Waiting on those from Puresmoker..), then will do a followup, but right now, I think it can only get better from here - if I can get a manual battery that fits, it's *possible* it might equal the 510 in throat hit. Will reload some more carts with same fluids on cleaned 510 and 201 attys and give it a few more cycles, but certainly do not regret buying the M201 (and now additional M201+parts from litecig)