I also wanted a 912 but the other cam that fit my 48* motor had been sold, so I didn't have 2 cores for them to grind on. With my 1.7 rockers a 912 would also have been harder on the valve train hardware. I don't like regrinding cams but cores are getting very hard to find unless you want to buy a billet.

But back to your question, I vote for the roller over the flat tappet. Less risk of wiping a lobe, less oil requirements. But there are a lot smarter guys here than me on this subject.

I may spray this motor again with just the fogger so I kept the 114*.