Just to notice: Front-mount rack mixers do exist, and can create a smaller rack, plus, especially if playing events, I'd say a rack not having a top-loaded mixer is a lot more practical.
Also, do notice that some of the pedal/effects loopers has programmable send/returns, mix-in and/or dry/wet mixing for each loop, which means they can replace a mixer - while simultaneously allow hooking up pedals, and further will allow wiring the whole shebang in series or parallel in different orders, preset by preset..
Rack mixers, like the Behringer 2U
XR12 and the 3U
X AIR XR18 (more channels and wifi) both comes with build-in effects, network and USB interface, has a multi-bus system for doing send/returns to/fro effects, while the 4U
X32 RACK additionally can do eight effects and can be expanded with more hardware.
While this is indeed very sexy, due to being digital, there's nevertheless a certain latency involved.
The pedal/effects loopers, on the other hand, do the routing/mixing in analog, so latency is by far non existent.
Whether or not latency is important depends on how much it is and how much or little you'll be able to actually feel it
Do note that sound travels ~340 meters per second, so 5 mS latency is roughly like standing 1.7 meters from your rig (340 meters / 0.005 seconds).