So does the LtAP have the USB 3.0 bus? Would that be better for the mPCIe speed?
The "full" LtAP has two miniPCIe. While the bottom miniPCIe is USB 3.0 and has two SIM slots, the top miniPCIe is USB 2.0 (and one SIM slot).
See the block diagram:
https://i.mt.lv/cdn/product_files/LtAP-2HnD_211117.png
(You'll note if you use the top miniPCIe , the USB port cannot be used)
Now if you look at the performance specs, you'll note the ARM in the wAP is slightly more powerful than the MIPSBE in LtAP. Additionally, the wAP lists for US$70 less than the LtAP, so if you're planning on only one modem, the wAP R ac is pretty handy.
We've used wAP and LtAP, but IMO if you want two high end modems, using two wAP devices gives you some hardware redundancy+VRRP. While the 8 SMAs needed for 4x4 MIMO with two modems inside makes the LtAP pretty bulky - in same case this may be handy. But the flexibility of the wAP is why we generally use them.