I have a lot of experience of Draytek 2860s having run one with load balanced Ethernet to local wisp and ADSL connection 4Mbps and 15 Mbps but we upgraded to FTTPoD and have 330Mbps and switched to UniFi total solution for better or worse. We both have large UniFi AP installations (probably 40 APs between us).

I put in a 2862 for my brother with Ethernet WISP WAN at 40Mbps and 4 Mbps ADSL (I shunt slow email traffic down the ADSL, and a few other bits, the WISP isn't perfect so keeping the ADSL makes sense). He is now looking at an additional Satellite WAN at 100Mbps or 4G connection, and ultimately maybe both or dual 4Gs.

Connections:

• ADSL
  WISP Ethernet WAN
  4G Connection
  Possible Satellite Ethernet WAN

Don't need Wifi.

2865Lac
This will support ADSL, WISP WAN, and dual 4G connections and load balance between all three. But wouldn't support a second Ethernet WAN

2927Lac
This will support WISP WAN and dual 4G connections, plus an additional Ethernet WAN. That Additional WAN could be used to support either ADSL via modem or Satellite WAN.

2952
Dual Ethernet WAN with dual 4G so same 2927Lac

3910
8 Ethernet WANS, much more expensive and would need separate 4G & ADSL modems. And might make him wince on the price

Is there anything I am missing?