ExpressVPN

Hello,
Hope not asking redundant questions, I did try to find my answer but I want to get a consensus confirmation.

Here is some history.

  1. We built a new house
  2. The house has the main house and a 40x40 pole barn (metal), that in that 40x40 (overall) it is really a 2 car garage/RV barn/apartment
  3. Calix GS4227 (ISP gateway) → CRS-317 (in routerOS mode, not switch) → CRS-309 via 802.11ad 20g link (metal buildings are giant faraday cages)
  4. Network has eeros (for wireless) and are set in bridge mode.

Everything works as setup.

I want to put a VPN (client) (preliminarily ExpressVPN or NordVPN), both have configurations for Mikrotik
My thoughts were in my setup, if I put it in the CRS-317, that should cover my whole network

At this point I am thinking logically it is doable. Having said that, before I jump can anyone speak to network speed over a VPN on the CRS-317? VPN will add overhead to that router.
If I were to install say ExpressVPN on CRS-317, can I expect to run it into the ground?

Little more info:
ISP D/L 2.5
ISP U/L 1.2
We run fire TVs cubes (3-5, mostly 3, 5 well future)
There are only me and wife that live there, potentially, casual extra user on wireless now and again.

My other recourse would simply license each of the appliances. (and maybe just do a few, I think I get 5 license with a VPN purchase.

I would be interested and much appreciative in experiences pros/cons