One has to keep in mind that Vicker K in not an upgrade for tommies is an ability available to the M3 halftruck and can be used in different sqauds.
The main options are RE, IS, and the potential one officer squad. On the officer the Vickers does well and fits well. But the fact that the Vickers comes via the M3 and not as an upgrade for the officer shows how it is intended to be used on other squads.
REs are not good fighting squads with their first and only combat bonus coming at vet3. I know you have argued for putting LMGs on them in the past, but I don't think it is an efficient use of munitions at all. Also the only way to somehow see a point in it is if you lock yourself to anvil for heavy sappers.
Now without accurate stat or sufficient test is rather hard to respond to the question if it worth using on IS.
If rhe information provided by patch notes is correct and it has DPS at ranges 0/10/15/20/25/30/35:
12.53/10.81/8.44/7.13/5.99/4.93/3.97 I would point out that the weapon better than Bren with a
DPS 4.14/5.09/5.56/5.81/5.97/6.39/6.86 even at ranges close to 25 so it better MID to close but probably only worth the extra munition if used in ranges under 15.
Even with bad moving DPS it still better than Bren that has 0 moving DPS.
At the end of the day Vikcer K is not designed around IS and I do not like what OP is actually suggesting which is replacing the Vicker-k on m3 with Bren. If one wants Bren for his IS one can get them by unlocking the weapon rack instead of calling the M3.
I am quite sure that the DPS in the patch notes are wrong, because I have seen them being wrong before when the exact changes were stated.
No one knows how they calculate them, but let's assume they are roughly what we need to expect.
By pure stats, yes, the Vickers K is okay. Bear in mind it costs way more than the Bren, so it having an edge should actually be the case.
My point is that the Vickers does not fit IS. IS cannot use its benefits due to the out of cover bonus. If the Vickers is not designed around upgrading your main unit, there is not a big reason to get it in the first place, thus the design is broken. RE spam is far from viable, and we actually have indication that the Vickers potentially does not have the stats it should have. Regardless, as UKF, you're stuck with Sections, and the M3 providing the Vickers to your Sections is not helpful.
Fact is also that Enfields are long range weapons, even more so than Grenadier Kar98s. They synergize best with other long range weapons.