I think you have a misconception about NM's low health pool. Currently my levelling trader is 218. In a full on DD setup, with no regards to hp at all. She's solitus. She has 14.5k hp. Had she been NM with the same gear, it would only be about 1k lower, and she's have access to NM cocoon (which is my opinion is worth more than 1k hp) At endgame, most hp and nano come from gear, the subtle differences in the breeds isn't that much. And especially NM get tools to overcome this with their cocoon and reflect perk. Also NM get better usage of some nanos (NBD).
With regards to healing, get 2 fast weapons and dualwield, and with maxed Accumulator you won't even need to heal. If I were to reroll, I'd choose NM any day.