Replacing Fortigate80E with Ubiquiti suggestions?

Hi Guys
(quick overview of network)

2 WAN lines from a main and backup ISP run into a Fortigate80E firewall. The firewall is directly connected to a UBNT gigabit layer 3 EdgeSwitch 48-Port EdgeSwitch which handles core switching and does have L3 capabilities. This switch then connects out to 11 smaller access switches that go out to banks of desks. The company has roughly 150 users atm and will reach 200 by the end of the year. There are no on prem servers and almost all traffic will be voip, web browsing and accessing files off cloud storage. We also have about 10 unifi pro AP's and 2 cloud keys that manage wireless networking.

My manager has requested I look into replacing our current Fortigate80E firewall with an offering from Ubiquiti. (The current firewall isn't under enormous stress, this is more for future-proofing project and hopefully being able to centralise management around a ubiquiti console)

My first thought is seemingly the most powerful firewall offering from Ubiquiti is the USG Pro 4? However, from what I have read it doesn't seem more capable than a Fortigate 80E? maybe more of a sidestep, besides the obvious advantage of centralized management with the current switch and ap's.
I was also thinking for a company of this size, surely it would be better to have a separate firewall and router to deal with core routing. Perhaps a USG Pro as the firewall and maybe another Ubiquiti router to handle the majority of internal routing??

Any thought appreciated :)