I have a Dye Sublimation printer, I was very close to getting the P-400 but I went with the Sony instead. I can't comment on consumable costs for it today, but I know 3 years ago when i got my Sony, both were very expensive, like 50-60 cents a 4x6. Canon has some newer ones that are in the 28c range. As for quality I don't think anything beats a good Dye Sublimation, the speed is pretty good, the print comes out completely dry and water proof due to no ink.
I will also comment that the ribbon/paper packets for my Sony are harder and harder to find, since nobody makes generics. I don't know what I'll do when Sony decides to stop supporting this printer all together. I would imagine it's no different for any other brand, the market for Dye Sublimation just isn't that big. But the quality is fantastic, of course my $100 Canon ip4000 makes fantastic prints too, and isn't limited to 4x6
Is the Dye Sublimation print quality better, probably yes, but is it noticeable? not really to me.