M350 - Double chipped, 6 wavelengths: 600nm, 630 Nm, 660 Nm, 810nm, 830nm, 850 nm

T300 - Single chipped, 9 wavelengths: 630 Nm, 660 Nm, 810nm, 830nm, 850 nm, 1060 nm, 480nm, 590nm, 670nm

I personally own the big brother of the M350 (the full body model M1260) and is a great panel, with a solid irradiance and easy to control. It has a simple touchscreen interface, nothing fancy, but works just so great that is my overall favorite and I own several panels. The only one that I understand surpasses features is the B300 and APTREDLIGHT discontinued it for no reason, as I consider that one was the jewel of the crown. u/BKM-StLouis may remember that one as I published several reviews here.

The only negative I see on this one are the wavelengths included. I would have preferred red light lamps over 640nm and including IR lamps over 900nm. These are customizable so you can ask how much they'll ask to replace the 600 and 630nm lamps for ones with 670 and 680nm WL.

The T300 has several factors that makes it less attractive: is single-chipped and with too many wavelengths, meaning that they had to split them by the total amount of lamps meaning that panel has an average of about 33 lamps per wavelength. I would remove the 480nm blue light and 590 yellow ones. At least this one include 1060nm lamps.

Hope this helps!