Taking Riverbed Steelhead out of service

This may be really obvious to people with Riverbed experience but I'm more of a core / MPLS guy so please bear with me...

From what I can see Riverbed SteelHeads auto-discover each other across the WAN, optimise whatever traffic they can and pass the rest through unchanged.

I also understand that they (can) "fail open" if power is lost. I can imagine the pass-through traffic fails over quite gracefully but surely if you just turn a unit off (or physically remove it from the traffic path) then any optimised flows are going to break?

If I want to remove these devices from service, would the cleanest way be to configure the them to not optimise any flows, give it a few days for any long lived optimised flows to die off and then decommission?

Thanks!