GreenScorpion, I had a few guys with banana shaped guns and a lot of mould lines to contend with! Nothing major but it slowed me down.
The thin lasguns and such should be a nightmare to reshape due to resin bending :|
Most of my resin parts are small enough that there is no major bending along the larger dimension, but it does make me stay away from larger stuff like vehicles, as I am just not very comfortable with reshaping large stuff.
Will await your Medusa with interest 
The lasguns I've seen haven't been too bad either in terms of bending, a little bit of hot water and they popped right back into shape. Honestly, for me to most annoying bit is the flash between the barrel and lower handguard/rail, which is tough to clean out without scoring the barrel itself.
I'll echo Jud in that the mould lines have been a real pain, and keep showing up even once I think they're gone. 