Pressure is pressure. You probably didn't have the regulator pressure turned up high enough on the pancake. The only down side to the pancake is that it makes very little volume, but air tools don't need much.
I run my 5HP compressor at no more than 120, you can get 120 out of small portables. I have one that is similar to a pancake with a different shaped tank. It makes 120, no problem.
You may have your 7.5HP monster cranked up to some pressure higher than what a pancake will make. If you do I would not recommend using high pressure unless you really need it for a stubborn bolt. Your air tools will last much longer with lower pressure and run only slightly slower, not enough to notice.