Check test results of both devices but keep in mind results from Hex are ROS6 based, AX Lite are ROS7 based.
I did some rudimentary testing with AX Lite using 3 VPN protocols: wireguard, zerotier and ipsec.
See here:
http://forum.mikrotik.com/t/hap-ax-lite/164010/1
I didn’t find any hEX results in that thread
Logical.
I didn’t say I tested that one (I do have it, was my very first MT device).
Do your own testing 
I was also referring to test results on product pages for both devices.
https://1drv.ms/i/s!Aukw5KCzXdEthpw4MTLTn3wqXMmLDQ?e=L6hcwG
Rother mixed picture, dependency from pocket size.
What do you think?
Additional thoughts:
As I just noticed, hAP AC2 is not much more expensive and outperforms both hEX and hAP AX Lite.
I just don’t like it because it’s warming issue.
However with wireless off hopefully no warming issue exists.
not able to SCAN wireguard QR Codes on mobile phones?
How to Scan QR Code.
It is not shown fully in Mikrotik Windows.
It shows half.
Help…
AX3 is ARM64!! (7.12rc1)
and for AC3 too!!
BTH is only available in beta versions of ROS for now. You need to install beta version of ROS if you want to use BTH.
I tried it with a hAP AC2, upgrading from 7.11.2 and got a boot-loop. Slow: boot, crash, reboot. Fortunately I was able to downgrade (fast SSH through several boot-crash-reboot cycles) and regained control. So I will wait for a while to install 7.12
It was in RC1 changelog.
==================================
Where I can find beta with BTH with changes in RC1?
As @holvoetn said:
It worked for me just fine.
new BTH will come in 7.13beta1
What is the difference?
You will see when it comes out 
Hello, greetings, my name is Hector Prado, I live in the United States. What do you need to participate in this project?
my email is hlp937@gmail.com
Just download 7.12beta to an Arm router.
I think that mr.Hector here is talking about what is needed for another relay station for BTH.
I think that best option is to contact Mikrotik support directly.
don`t working on my hap ac3 with 7.12rc1
Normal.
Wait for 7.13 beta or use 7.12 beta 9.
Feature has been disabled in rc and stable.
ROS 7.12beta9 + WinBox 3.40