About AliExpress : I bought my Sony PCM D-100 used from them. They were being sold at a decent price (around 550USD). At first, I was suspicious: Why does so many Aliexpress seller has some D-100 to for sale while none of them has other models in stock, like the M-10? Could it be a counterfeit lineup or damaged/sub-quality units? (Some AE resellers still have some D-100 for sale right now.)
Since I really wanted to have a D-100, I overcame my suspicions and bought from a seller that offered decent warranty (satisfaction/few days; one year/defects).
Shipping was quite fast (less than 2 weeks). At first, I kinda freaked out because I thought my recordings would be nearly silent. But I guess there's noise and hums everywhere. For sure, it sounds way better than my previous Zoom H4n recorder. I also found my EM272 to be a bit more silent than the internal mics of the D-100 (though sometimes, I'm catching up some RF noises with the 272 when I record near my internet router, don't know if it's normal behaviour or not). The internal preamps are also pretty silent when I'm using contact mics as hydrophones.
One other thing to mention : They have put sticker with Chinese characters on the screws so you can't open it without breaking the one-year warranty. Again, I don't know if it's usual or not...
Overall, I'm quite satisfied with it but whish I could A/B test it with an other D-100. I did it with an old Sony PCM D1 and I though the noise floor was quite similar. It's often hard to differentiate noise floor and self-noise. I think I either must have bought a legit unit or a high-end counterfeit !!
As for the shotgun : Finally, I have decided to go for a ME66 rather than a MKE600. Even though it might have less bass response than the 600, it appears to be more sensible and directionnal which seems to make a better companion for the D-100 in a sound hunting situation.