SMB / Lift bag as a backup device

[elan]

I want to get an SMB/Lift Bag to have it as a marker and a lift bag in case I need it in emergency if both dry suit and BCD fails. I'm looking at this Halcyon Marker which is claimed can be used as a lift bag as well, it' provides 52lb lift

Super Big Diver's Alert Marker, 6' (1.8 m) long, closed circuit

Halcyon Surface Marker Buoy's 14.002 *Buy Halcyon at DIVESEEKERS.com 888-SCUBA-47

The configuration I'm planning to use it for is dry suit, double HP tanks 100 or 120, 50lb wing. So I plan to rely on it in case i need to recover me and my rig in total failure of both components (dry suit/wing). Do you think it's a good option or I should better look at having 2 separate devices. say SMB and 100lb lift bag? I like this particular marker as it's pretty functional, has LP inflator and relieve valve as well as SS ring and reflector, seems to provide reasonable lift.

Thanks in advance