Sounds like the bike for you. Good cross bikes are fast and light. They won't be quite as light as road bikes, because of the tires if nothing else. Ya won't be able to do some MTB trails but general off road is what they're made for. A bonus, is you...
Tom Ritchey was a Mountain Bike manufacturing Pioneer. Ritchey originally made high dollar handmade Steel Frames, and complete bikes. Like Specialized, Ritchey was an early manufacture of Mountain bikes, and no one manufactured parts for mountain bik...
Check out Masi, Orbea (spanish), Guru, Colnago for road bikes. Not sure about italian mtb companies but if you want an expensive mtb try Scott bikes for dh/fr.