I thought I'd read a while back that these are only suitable under heavy loads...recently I read an article that counters this saying they are suitable for all workloads..
Here's my question..
Why wouldn't I use the PVSCSI or VMXNET3 if my guest os supports it?
See this KB: http://kb.vmware.com/kb/1017652
Since 4.1 it looks that PVSCSI can always be used:
"The test results show that PVSCSI is better than LSI Logic, except under one condition--the virtual machine is performing less than 2,000 IOPS and issuing greater than 4 outstanding I/Os. This issue is fixed in vSphere 4.1, so that the PVSCSI virtual adapter can be used with good performance, even under this condition."