Yes, given the description of your diving ('I only ever dive warmish water (rash guard and boardies - 5mm full wetsuit) '), the lift is quite adequate. I dive a 30lb wing with steel backplate and steel cylinder (HP100 or HP120) and 30lbs is more than enough. With an AL cylinder, you will be fine.back to me original question; is the 28lb wing enough with 12l alu tank use?