This is not a distinct feature of the Summit cam. Many - if not all - of the aftermarket cam manufacturers grind their "mild performance" cams for Pontiac V-8s this way. Summit buys their cams from one of these other grinders.
When you read the cam specs, you should divide the lift of the aftermarket cam by the lift of the OEM cam at the SAME .050 lift duration. (Don't use advertised duration.) This takes the duration factor out of the discussion. You'll see that the lift ratio is usually right about 1.1, which is the same as the ratio between 1.65 and 1.5 rockers.
Though it leads into a far more protracted discussion, if you use 1.65 ratio rockers with one of these copy-cams, you can expect an additional 10% lift gain at the valve. When doing so, the valve train geometry must be fully checked out to prevent seal crashing, coil binding, etc. In most - if not all - cases, the spring seats will need to be milled (recessed), longer valves will be required, along with adjustable locking nuts and longer push rods, etc. To take advantage of all that lift, the heads would need some work ... and the upward spiral begins, followed by the downward spiral of your bank account.
