I have both the SC52 and Xeno E03 and I like 'em both. Both are XM-L and with a 14500 there's not much difference in effective light output.
The SC52, IMO, has the best UI. From off, press > .6secs and you are in low, less than .6 secs and you are in high. Press and hold to go L-M-H or H-M-L (depending on where you started, H or L). Double press to switch through stage 1 and stage 2 at each level so essentially you have 6 different lumen levels. It will remember what stage you set for each level too. From on, press < .6secs to turn off.
The SC52 is shorter by 3/4" but the head is a bit larger. Weight for all practical purposes is close enough to be the same. SC52 has a clip but no real lanyard attachment. The E03 doesn't have a clip but does have lanyard attachment holes.
Of course the E03 is rear clicky and the SC52 side button.