not much worse of the current state... (and of the state of LazyGetter LazyRef that it will replace)
Actually I have introduced it to avoid onDemand updates (the default is still onDemand). 
A user can set it false (mostly in analyzer or other form of "very" const iterations)
and see the current state of the container w/o triggering the LazyGetter.
OnDemand tracker is not thread safe, at least not within the same event.
edmNew::DetSetVector  can be made "thread safe"  at least to avoid data corruption.
It will never support concurrency in a single event, at least in the current design and with the current performance. 
(and this is not just DetSetVector, more the whole "design" of tracking at HLT).
I do not think that HLT is planning to run multiple thread per event.