no they dont feel heavy, the bindings are right next to your foot so they dont add much to the swing weight, and generally the heavier a binding is the more durable it is and durability is way more important in my opinion.
I have ridden salomon S812Ti's and Look P12 Jibs, and there is not a big difference in terms of the weight. I would ride the looks any day over the salomon bindings. SO much better.