Ye I dropped my pure melee build. The game design just wasn't meant for it. You get locked into linear striking and can miss super easy if not directly on target. Plus you get raped by gunfire if you try to move around. The overall game design just wasn't meant for it.
I am still using Shotguns though, but I just found a beast weapon setup.
The Particle Rifle just destroys everything. It's the first time I used it and it is beast. Unlimited ammo and if you tack on Cryo Ammo, it's an unstoppable Freeze Ray. I'm just steam rolling through Insanity now. I wipe out groups of Cerberus like nothing. I eat the turrets up like candy. I'm really interested to know how other ammo types work and how strong they can be. I would imagine very good.
I just love Cryo Ammo because you can almost instant freeze enemies and shatter them. I don't even have it maxed out yet. I'm gonna get my entire team armed with it,

. I may drop the shotgun. They are just so heavy and the range is horrible. Although they are very strong.
I can one shot freeze and shatter on a second with close enemies using shotgun. So I'm not sure what I want to do with it. I have mostly weakening and support powers, so I'm really only attacking with guns atm. Garrus and EDI are probably gonna be my main companions. I had Ashely die so I got that other guy from ME1. I'm gonna send him to the Specters and leave him there. I never really did like him. Plus he kind of sucks imo.
I'll have Garrus and EDI both with Overload and myself with Energy Drain, so bye bye shields. Plus everyone will have Cryo Ammo and I'll be floating people all over the map with Pull.
Oh btw I got the Mail Slot Achievement.

Particle Rifle FTW, easiest way to get it. Just blast it on the eye hole. Also for the guys who carry the big shields, Pull is the ultimate weapon if you don't have a Particle Beam. Pull will take the shield from them leaving them helpless. You don't even need to upgrade it.