if you've ridden both, how is the 8v better?

Both oil pumps? The 1100 only has one???

Sounds like gross incompetence to me. While a tappet failure on any engine is possible replacing it and the cam is a simple matter of taking out the rocker gear and pushrods, dropping the sump, removing the timing chain and sprockets and pulling the cam. The followers drop out of the bottom of the engine, new ones can be inserted through the front cam bearing and stuck in place with grease, the new cam slipped in and everything reassembled. I cannot see how a light alloy pushrod could 'Punch through' a chilled cast iron tappet. It's not going to happen. The Guzzi engine is so simple I find it hard to believe anyone claiming to be a 'Mechanic' couldn't put one together right.

Mind you I've seen some pretty stupid shit done over the years. Some of it by me!

Oh no John, really sorry to hear about this. That bike was about as clean and solid an example as you could hope for, which is why we both bought it, so even more of a blow when that happens, and as you said, you avoided an 8v for this very fear. I'm pretty sure it's nothing I did in my ownership as I only had to do minimal usual maintenance and one rocker cover gasket replacement I seem to recall (but apologies if it was somehow?) and the guy I bought it from was fastidious too, so that's really bad luck for you. And the garage just compounded the problem. I hope you enjoyed those 7 months with it though. Are you going to get another, or stick with the LeMans. That should be a satisfying rebuild when you've completed it. Be good to see it when it's done.