Regarding cleaning, I'd rather use a soft cloth with medical grade alcohol to clean the shell.
Regarding an upgrade to the FDX1, the question mainly is what you are looking for, and secondly what source your are using.
The IER-M9 is clearly a much better IEM overall, but also very different in it's character.
The M9 is extremely refined and precise, very detailed while at the same time having a more natural timbre than most BA IEMs. It presents music in all it's nuances and detail without sounding analytical. But it's on the relaxed side of presentation, not very dynamic. In that sense the FDX1 is maybe more engaging. I do feel though that the M9 needs a really good source to show what it's capable of.
If you like the FDX1 and just want a big upgrade, take a look at the UM 3DT. It's a big step up from the FDX1 IMO, but more similar to it with the 3 DD drivers and the boosted sub bass and upper mids. This IEM is hard to get a good fit with (huge nozzles) and it needs some additional damping mod (easy DIY) and deserves a really good cable and source. But then it's VERY dynamic, has excellent detail, layering and soundstage and perfect timbre.
I love both, the 3DT is more intense and lively, the M9 is more relaxing and comfortable, laying out the musical details in front of you.