I also have kept the Dexcool in. No issues whatsoever in any of my cars that have had it (97 Cavy with 184K when I sold it, my C1500, the Bonnie, and the 'Hawk). As long as the fluid is topped off it'* fine.
It'* been 4 days/350 miles since I retorqued the upper and it'* holding up real well! I don't have that puddle anymore and the lower intake is drying up where the coolant was running down. The back side of the upper I think is leaking. There'* a light dirt/moisture mix in the coolant vanes of the lower intake. Nothing is puddling, but it'll only be a matter of time before it does. Hopefully it'll hold out until somebody makes an aluminum discovery!