Well, if you *liked* the R90S, have a hard look at any Tonti LeMans. They are every bit as capable, maybe *more*reliable.. Guzzi didn't put the rectifier inside the engine cases, and more fun. Captain Obvious here, but as far as I'm concerned, a motorcycle is all about the motor.
I've had 13 Guzzis of all sizes and types in the modern era, from the early V700 through the Norge, small blocks, big blocks, 2V, 4V, and I've loved every one of them. It's all about the motor. If you are a gear head, and it sounds like you are.. give one a try. They don't let you forget you are "operating a machine," one of the things I like best.