I have a 45 Clem L with a 78 cm PBH. I don't have experience with the 52 Clem L but had a 51cm Appa that has a similar geometry and 650b wheels.
Compared to the Appa, the 45 Clem L definitely fits smallish (longer/taller stem, seatpost pretty extended) and the chainstays are shorter so I had issues with heel strike with a couple of racks. On the flip side, the 51cm Appa was almost an ideal "riv" fit for me. For most riding, though, variables other than frame/wheel size tend to dominate how the handling felt. The only exception is at low speed while navigating narrow and tight spaces in urban areas. In that case, I definitely prefer the 45 Clem L over the Appa as I found it easier to execute maneuvers.
--Ed C.