^^ It's a fine move.
You'll find with the M10 you will sometimes need to run the PS/2 into the mic input on LOW in order to get decent levels, even at a rock show. As fluffed constantly on this board, the M10s pres are decent, so that's totally fine.
In the longer run, the Aerco is the smallest thing other than the tinybox, and it sounds pretty amazing - competitive with any of the high-end pres. I thought about going that route but I stealth rarely, and when I do it's usually not in venues with much of a search.
Ideally, I'd think having a 48v tinybox for stealth and something else of your choosing for non-stealth is the best move. The tinybox is certainly better than the M10s pres. I haven't heard an A/B of the tinybox vs. the littlebox or any other pre for that matter, so I can't say I have an opinion on how it stacks up, other than that hi and lo and I tape together a lot, and he's tried out lots of configs at different shows, and you saw his opinion. It is a fact, of course, that the LB can have output transformers added, and those will impact how the pre sounds, and transformers aren't an option on the tb.