I've tried to make use of the melta previously with my orlick gang and it's very very difficult to get any bang for your buck. It has something like 73 strength and minus 20 to enemy defence but by the time I got it everybody I faced had heavy carapace armour and it would on average do 2-3 damage. I think having precision shot helps. Super close range, two shots and you're done, usually get mullered trying to close the distance. It's a peak level weapon for killing the unkillable H2H beast but I'd prefer the flamer myself because YOU CAN'T DODGE FIRE! On a side note I've recently started with van Saar and was amazed how good the suppression las is. It's ALMOST better than the combat shotgun, but doesn't have knockback for blasting gangers off walkways. Melta is a luxury item to play around with once your gang is 'finished'. I do find that limited ammo guns are best for leaders who give orders so often they don't mind only having two or three shots per battle.
Anyone else notice that web weapons and grav guns have been added to the weapons proficiency tab in skills? Delaque on the way.....