On one hand, the firmware is better than it was on August 2, 2022. At the same time, it still leaves a lot to be desired.
I personally have a firmware build using the gl-infra-builder from a few months ago, and it’s relatively stable. That said, it’s still on a QSDK 4.4 kernel and… well, yeah.
Realistically, you can get between 200-300 mbps on a clean OpenWrt build using WireGuard for the A1300 see also (here).
You can get an easy 300mpbs on WireGuard and 150-180mpbs on OpenVPN using the MT3000 (which has it’s own firmware issues, but is in a race condition with the AXT1800 for clean OpenWrt support).
The AXT1800 will in theory give you ~600mbps over WireGuard, and tops out at the same 150-180mpbs as the MT3000 on OpenVPN.
In my mind the question would be whether you really need the extra 300mpbs that the AXT1800 offers. If you are purely concerned about speed, you’d be better off getting a low powered Intel appliance for not much more money that could likely easily handle 1gbps on WG or IPSec. There are a number of solutions that can do this if you’re not super concerned about power/size/weight. If you’re on the road, 600mbps is kind of overkill, IMO. I rarely stay anywhere that the 50mpbs you get on OpenVPN via the A1300 is actually limiting.
tl;dr - Unless you’ve got a GL.iNet router that’s got stock OpenWrt support, the firmware is going to be a crapshoot.
tl;dr (2) - If you really want the “best VPN speeds possible” you probably don’t want a low powered ARM device.
tl;dr (3) - If you are looking for a travel router, the functional difference between the A1300, the MT3000 and the AXT1800 is likely to be negligible in terms of VPN speed.