I haven’t tried the Barrett. I always thought it looked primitive and chunky. But that’s just from photos. Just never appealed to me.
Tough choice, A2 covert or M2. Covert allows more barrel option options but it can look a bit odd with a longer barrel. While the regular length handguard allows more additions on the rail. Flir/night vision use, less issue with longer scopes/sunshades and or eye relief if you have anything attached on the top rail. Gives you a lot more railestate.
I’m partial to the full length rail over the covert. I like the 22” 308 barrels and 26” for 338lm, 6.5 CM etc. The short barrels look cool and are handy but you pay for it in ballistics.
I’d probably go M2 over the covert. First world problems!
The Barrett is a better built rifle than the DT.
Barrett is more similar to AI. DT is probably a step below that.
Nothing against the DT, they are really cool rifles if they are your thing. I play with the idea of getting a DT from time to time even.
The advantage to a DT in Canada (or AI) over a Barrett is the support.