The Baby borns and those type of pouch can be pretty hard on your back too for long periods with a bigger baby. I ditched mine once they were around the 6kg mark because it just felt like it was pulling my balance out kwim? Have you tried him facing outwards in the HAB? Maybe that's what he doesn't like, not beeing able to see? With the slings (I have a hotsling I use it Alister now and love it) they aren't meant for all day carrying for that reason. One other thing I can suggest is go to carryingaway - they have a checklist for choosing the right sling/carrier depending on how you want to use it.