Not sure what all this commotion about the MOTU M2/M4 is. It is practically the best overall interface when considering the features it comes with, specs, and pricing. As mentioned by others the biggest downside is that for some it may lack power for the headphone output, but it will be more than adequate for 95%+ of headphones and you can determine ahead of time with a simple calculation if this will be a problem since all of the specs are public and verified. All these claims about it sounding such and such or not as good as another interface is simply nonsense, and probably a result of someone's bad mood that day.
If one wants quibble about a 0.3 dB rolloff at 20hz, well then I don't know what to tell you. One can easily AB this infinitesimal "droop" with EQ on any system and you will not notice any difference. Also, I think some of these minor "issues" with the measured specs are not even present in newer revisions of these products since they changed the chipset and specs improved marginally across the board, but I don't have any measurements for you in that capacity. The issues with a loose USB-C connection might simply be factory defects since I nor anyone I convinced to buy this device has had that problem.
ASR does not have many ADC's measured so it looks like the MOTU M2/M4 is perhaps a "mid tier" performer in terms of SINAD to all the others measured, but when you consider all the commonly available interfaces out there in this product category with 3rd party measurement available,it would easily be in the top quartile ("light blue bars" on the ASR comparisons) and probably even in the top 5%+ of interfaces at least. Consider YouTuber/interface reviewer Julian Krause's measurements for dozens of interfaces:
When comparing to actual similar products the MOTU's budget category is obviously a diamond in the rough and outperforms most interfaces in many regards. You have big brands and well known interfaces here with problems like THD+N in the -40s, crosstalk at -38 and monitoring output impedance in the 20's (which in some cases may have the potential to change the frequency response of a headphone more than -0.3dB mind you, perhaps one reason not to get an Audient interface?). These are potentially bigger problems that one should be worried about, and I'm sure if many of these other interfaces were measured with the standard ASR uses there would be even more problems to be found. Better to deal with the devil you know than the devil you do not. MOTU M2 is still VERIFIED excellence as far as the entire market is concerned, if you want better pay another $50 for an M4 or pay many hundreds more for an RME Babyface or similar, unless you can deal or work around the flaws many other interfaces have.
Can latency be an issue if you do video work and need lip sync to work ?
The latency is quite low, don't think it would be an issue.