My Smabat NCO and M1 Pro order just arrived the other day. I agree with everything you wrote about the NCO. They have good, and different bass from what I usually hear in IEMs, which I think is due to their construction and venting. It's a really well-rounded IEM. Quick note about the eartips - the included ones are very good and work well in terms of fit and sound. The nozzles do not have any sort of ridge so if you change tips, you'll need something that will fit snugly by friction alone onto the nozzle. This will also limit the type of tips you can use, since you'll need a pretty exact fit. The nozzles are slightly lower diameter than I typically see. Fortunately I have no complaints about the included tips. The NCO are very compact, well made, and one of the nicest cable-down IEMs I've heard.
The M1 Pro puts the nail in the coffin for me and earbuds - after a lot of trying, I've reached the conclusion that the physical structure of my ear just isn't conducive to any sort of seal needed to get decent bass performance out of any earbud. Which is too bad, because when I press the M1 Pro to my ear so that it seals well, it sounds very good, but as soon as I take any pressure away, the bass goes away too.