After looking around the forums for DPS that is good with a high latency, these are the common responses:

SAM/BLM - Least affected
MNK - Moderately affected
RDM/DRG - Abit more moderately affected
NIN/BRD - Don't even try.
SMN/MCH - Didn't see any responses so no idea.

I'm getting into the DPS role and have raided with BRD/NIN/MNK/SAM. With 150 ping I cannot fit 2 ogcds most of the time without clipping into the next gcd.

So my questions are:
How much damage am I losing if I don't strictly follow the optimal openers and just try to spread everything out evenly (single weave everything), over the entire fight.

Second, are dragoons really that dependent on double weaving? I've looked at the CPM for DRG and it is fairly low for most fights.

Should I just play whatever class I want and single weave everything or change to a slower class like DRG/BLM? (All my friends are playing SAM already).