If you like the SC51 you will also like the SC52. I like the SC52 and have no hesitation in recommending it. The body design is different, as can be seen in photo's, and the switch is also different to alleviate accidental turn on's in your pocket. The body design doesn't strike me as better or worse, just different. The switch is much better even though it is stiff in comparison to the switch on the SC51. I really like the battery level checker where you click the switch four times rapidly in succession and, in response, the SC52 returns a specific number of flashes, 1-4, to indicate battery level. One is the lowest and 4 is the highest. The XM-L is very bright and floody. I have mostly used a 14500 in mine. The output on the highest setting is very impressive, but it does get warm in a hurry. The various levels in between the highest and lowest are spaced well. You can easily find the appropriate level for the need you may have. Only the lights with the "infinitely variable" control ring have more levels for your custom needs (which is why I favor them over all others). Yesterday I used my SC52 to provide the light necessary for connecting a number of components to an audio visual system where there was no light, and I have no complaints.
I was fortunate enough to pre-order my SC52 early. If you haven't ordered one and are thinking about it, or if you are waiting for delivery from the pre-order backlog, it will be worth the wait once it arrives, IMHO.