mddolson once bubbled...
Omicron bubbled: "I don't run doubles w/ a manifold. The cost is a touch prohibitive at the moment."
Ain't it the truth!
A single tank alternative is an H valve, with redundant regulators.
Free flows are common even in ice diving with antifreeze equipped 1st stages. With a redundant reg, you can shut down the free flow and switch to your back up.
MikeD
I just went down to price the whole thing:
2 Pressed Steel 100s
Tank Bands
Valves with isolation valve
O2 cleaning and stickers
With tax and everything (and a good deal) almost 1200 dollars!