Yeah, the Collectors can be hard. I've found that you can shake the swarms if you roll/evade. It takes 3 or 4 rolls to shake 'em off. The key is to blaze through the barriers and armor as quickly as possible. And take out the scions first. Their "toss a bucket of grenades into your lap" move is a bitch!
I don't know what to make of the weather effects on Dagger. It's different, it mixes it up, but I can't say that I had more fun. It was just different. The changes to FBW really surprised me, though. I wonder how that'll change FBW Geth gold farming?
And lastly, I spent $11 in ms points + a bunch of credits and didn't unlock any of the new characters or weapons. :/ Oh well. I'll be back for more and there will be plenty of opportunities to unlock them.