Rambling a bit here...
A lot depends on how far you want to take the contrast between figure scale and ground scale. Since 40k has no defined ground scale (e.g., 1" = 10 yards or whatever) and on top of that has no defined time scale (1 turn = 1 minute), you've got a free hand. (And the more you tinker with it, the more work you make for yoruself, even if it's fun work)
For me, it's deeply unsatisfying to see a table of a theoretically futuristic wargame, with weapons that should be much more effective than modern ones, where it's as crowded as the mall on Black Friday (pre-Covid, of course...) and the tanks regularly move a shorter distance than they are long. That's why I favor using smaller figures on a standard table with standard measurements; it comes a little closer to the spaced out battlefield that I imagine 40k ought to have.
The absolute worst example of this is actually BattleTech, which has absurdly short ranges for its weapons... There are plenty of rationalizations for it, but at the end it boils down to "We want to keep this game playable on a limited physical space with weapons that have limited ranges" which is fine.
I'd say from a plausibility standpoint, btw, that "tank-only" battles should happen on pretty clear tables; there shouldn't be a lot of cover for infantry with nasty anti-tank weapons to exist, or they would be deployed on the battlefield in support of or instead of armor. Kursk instead of Stalingrad...
It probably comes down to actually playtesting it on a table and seeing what gives a fun game.