Hi,
I agree about smaller canopies, but not for the reasons you're saying. Usually a collapse occurs when the angle of attack of ther canopy goes to a negative. This can be caused by turbulence. A higher loaded canopy is flying at a higher angle of attack (on the same glide path) so is less likly to encounter a collapse, however when it does collapse its likely to be more dynamic.
I had a couple of questions about airlocks. Bear in mind I'm coming at this with a number of years paragliding experience. Paraglider design experimented with an airlock type system and gave it up for two reasons.
Firstly, when an airlock does collapse, its likely to remain partially inflated potentially causing a more dynamic collaspe due to the additional drag on the collapsed wing section, and also meaning that section of the wing is more likely to get caught in lines.
Secondly, if an airlocked canopy does collapse and re-inflate that reinflation is likely to be in an uncontrolled manner. This 'shock reinflation' effect has caused issues with line and material damage, and problems with a further cascade of collapses due to the manner of re-inflation.
I'm not sure either of these would be an issue on a parachute canopy though?
Cheers
Hugh