This is a tough one...

I have read that no-cam sails will plane earlier than cammed sails because they are more flexible/less rigid and enable air/wind flow...

2 cam vs 4 cam... Generally, modern race sails are wide luff and have around 4 cams... more flat water orientated freerace sails have around 2 cams... On a lot of manufacturers websites, you will see they claim the 2 cam sails plane earlier, perhaps this also has something to do with flexibility/rigidity of the sail...

The general rule for cammed sails: more cams = more rigid rig = more stability = more top end speed.

My rule for wide luff race sails: don't drop them in the water

In general I thnk cams are good for 8m plus because firstly you don't have the same pressure in preplaning conditions to push the draft back away from the mast to create the early planing deep draft needed. Cams lock that draft in place and help the sail build momentum before the apparent wind speed picks up. In addition they are more stable creating less dragin gusty conditions helping you to stay on the plane in the lulls

Cams on big sails are definately the go. In the past they met a lot of resistance due to the difficulty in rigging them. Today the 4 cams Like Neil Pryde RS6 are easier than no cams. The mast goes nearlly all the way up the luff before meeting any pressure from the narrowing of the luff pocket. On the water the cammed sails are far superior and have a more controlled feel. The only time they are a bit of a negitive is in really light wind after gybing there may not be enough pressure from the wind to pop the sail. AS soon as you have moderate power this problem dissappeares. They are also faster