Disagreed.

Mark II L is too heavy, too slow (in terms of reload) and poor damage (damage bugs as I reported above).

If you like, I'll use Mark I L in my Renown to pwn your Mark II L.

Of course, we are talking about Blitz crew here.

For high level crew, use Mark III D of course. 

As Resolution/QE, you should of course use Mark III N, which gives so much more range than Mark I L.

Mark III N has near-BB3 range. Of all UK guns, in terms of range,

15*2 Mark I L ~= 15*2 Mark III D ~= 14*4 N
<<
16*3 Mark I L = 14*4 L
~<
15*2 Mark III N = 15*2 Mark III L (but L has faster reload and turret rotation speed)
<
Lvl 91 Lion I's 16*3
~<
Lvl 91 Vangaurd's 15*2
<
Lvl 100 Lion II's 18*3
<
Lvl 120 QV's 20*3

Given good gunners, it's quite easy to make 100k+ games in GB with Resolution. But you need to be good at sling-shooting.