The UK general standard is the Orange DSMB for normal ascents.
For most UK dives, the Orange DSMB will be deployed. Relatively few sites will involve divers ascending the shot line. Tide generally makes shot line ascents uncomfortable unless you are using a Jon line. The preference is always to drift with the tide.
The distress DSMB is the yellow one. However, this needs to be pre- agreed with the boat. If you want a drop bottle it will be your responsibility to bring your own and rig one ready for deployment.
Just a few weeks ago on a trip, the skipper asked what action the boat should take if a Yellow DSMB was deployed. Because our decompression commitment was going to be minor, 30 minutes or less, we didn't plan for a drop bottle. So in the event of a yellow DSMB, we just wanted the the O2 kit made ready.
Ultimately, you need to ensure everyone knows what the procedures are in advance and the equipment is set up ready for use. This needs to be agreed with the skipper and crew.
Within our club we avoid dual colour DSMB's (yellow/orange).
From the point of what stands out. As I understand it, orange is easier to see it you are on a boat. Yellow is easier to see if looking down from a helicopter. That was as a result of some tests done by the RNLI and Air Sea Rescue Services.