On my main RP-intended VHF, I run 2 x DEFILERS (600 m/s, 2.00) and 4 x ARCHANGELS (650 m/s, 1.00), mostly because I can; I typically run them separately/exclusively due to powercore.
That loadout is quite impractical, but it makes short work of NPCs that are much, much easier to line up. With my skill level, next to useless in actual PVP.
I use both depending on what guns I match it with... and also the faster debs I'd usually match with class 7s and the slower debs with the slower re-fire guns....
They help to match with the various gun stats out there, basically.