Hey! New user here (although I'm pretty sure I had an account X years ago - I used to discuss Denon buds back in the day - but it doesn't seem to exist anymore).
Anyway, I just picked these up on Black Friday at a decent discount. I most recently come from the Sennheiser Momentum Free (wireless but with a wire between the buds - which I actually kinda prefer in some ways, although there are downsides as well of course, and it seems like this style doesn't really exist anymore outside of more sports-oriented options), and before that the wired Momentum IEMs. So these are my first true wireless buds. I was debating between these and the Sennheiser MTW2, since I've really enjoyed the Sennheisers I own, but in the end these felt like the more high-end and "complete" choice feature-wise. I tend to want the latest and greatest, and the MTW2 are getting a bit "old", lacking high-res codec support etc. If MTW3 ever happens (who knows what will happen now that Sennheiser have sold off their consumer audio business) I'll probably give those a go, but for now the XM4s felt like the better choice.
Been using them for a few days, and overall I'm pretty impressed. I immediately thought they sounded really good (using LDAC on a Pixel 2 XL), with a very "big" sound. Warm, sure, but not dark or muddied. The lower end has great presence and power, and a bit of EQ easily brings the mids and highs back to where I think they should be. In general I just think these are fun to listen to. Definitely not flat or analytical, but they have an enjoyable musicality to them. I also feel like I can listen to these for longer with no risk of fatigue.
I'm not really a fan of foam tips though, they feel stuffy and too "present" in my ears. These hybrids aren't as bad as pure foam tips, but I really prefer silicon, so I have some Spintip 360s coming in based on recommendations in this thread. They were NOT cheap to get, I'm paying around €50 for two packs (four pairs), which I felt I had to do because I'm not sure which size will be right for my ears (I have weird unmatched ears where I always need larger tips in my right ear than my left). I also wanted to try the Spiral Dots, but those seem pretty much impossible to get a hold of here in Sweden.
Beyond that, the buds are working great. Good connection (they definitely cut out less frequently than my Momentums), good app with a lot of customizability (although I do wish you could control in more detail what single/double/long pressing each bud should do, rather than just having a few preset options), etc. I was maybe a bit disappointed with the ANC, but that's probably just because I've never had any headphones with active noise cancelling before and thought they would cancel more noise than they do. Low frequency humming and rumbling IS very effectively silenced, but higher frequency stuff (human voices etc) don't really seem to be cancelled out any more than with just passive isolation. And I've now understood that's simply a limitation in how ANC works, but yeah, I have to say I think this feature has been oversold as more "magical" than it really is.
I've also noticed the right bud drains noticeable faster than the left. I've only run them down completely once so far, and they mostly stayed within 2-3% of each other, but then the right one was suddenly (well, the next time I checked) at 10% while the left was still at around 25%. But I've understood this is also normal, or at least typical.