Bump for some of our resident experts
I can see using a bit of oil to lubricate the valve seal/valve installation, but I always assumed that, ideally, lubrication between the guide/stem interface came from the guides themselves. Being a turbo guy, I'm always worried about coked-up oil's abrasive nature and would think that oil baking in the guides would not be a good thing, but perhaps the combustion temps transfer fast enough to prevent reaching those temperatures.
Alex, I'm going to use some coatings in my engine also, though I haven't decided just how far I'll go, I'll have to see what fits the budget.