Apollo Mon L/R into Input 2 L/R of Axe FX (my monitors on Output 1 of FX3/or use headphones on Apollo or FX3). I Use my Apollo Twin exclusively as Mic Pres nowadays. I mainly did this so I can route Input 2 of FX3 to Output 1 of FX3 so I could use my studio mics in something like Discord. Otherwise, if I don't make a new patch in FX-Edit, I'll just add a quick input2->output2 for something like XY mic'ing an acoustic with the pizeo pickup from Input 1.
If I'm serious about a project, I like to record DI's for rhythm guitars and bass guitar, so having Input 5/6 from FX3 to DAW for DI tracks is amazing. I would have to otherwise route a SPDIF from FX3 to Apollo Twin due to lack of analogue inputs on Apollo from Output 3 or 4 from FX3. I only really do this if I want to edit the takes, then I'll re-amp the DI's with the edits to avoid artifacts.
I can't detect any latency from Apollo to FX3, but I'm sure it adds something incredibly small like 2ms or smaller. I think it really comes down to how low your HW buffer size is. The Mac Mini 2018 can handle HW Buff 64 with no issues when tracking. Keep in mind, you always want to monitor your instrument from hardware and not from your DAW. I use Pro Tools, so I keep Low Latency mode turned on so I don't hear playback when I've armed a track.
So in short: I route microphones (panned) from Apollo to Input 2 of FX3, powered monitors on Output 1 of FX3 (I keep monitors on a separate power strip so I can turn them on/off easily), track with FX3 Input 1 Input 2 L/R and DI's simultaneously if I really wanted to. I always record Input 2 L/R on their own separate mono tracks.
I used the setup you posted about first, and it works just fine. This new way is an easier for me to mic acoustics or vocals without swapping cables on the Apollo Twin.