As far as I know, my hair likes hydrolysed protein so I'm not worried about that.

You are right about guar hydroxypropyltrimonium chloride. I checked it on the Science-y Hair Blog and it is listed as a polyquat with higher build-up potential. It's relatively low on the lists though, and I don't think I've ever used a product with this particular polyquat, so who knows.
F - LP - HD - NE
Fine, low porosity, high density, normal elasticity
Hairtype 2c

Low poo: Weleda Oat Replenishing Shampoo
Protein: IAGirl's gelatine treatment
Detangler & LI: KCKT
Styling: KCCC

Beauty Is Not a Number