Im looking for info on Dive Rite transpac harness or Halcyon Eclipse setup, this is for streamlining for spearfishing while scuba diving and later for tech diving.
You can't really compare these at all...
... the transpac is a soft harnes, the Halcyon is a hard plate.
If you're ultimate goal is "tech" diving, my suggestion would be to not consider a soft harness. I find they lack the stability of a plate.
You'd be better off comparing the transplate and the Halcyon.
The Halcyon wins that hands down. The wings are better quality (DR still use a PU inner, I think?) and the harness is way more streamlined than the transplate. You can always add a right hip d-ring to the Halcyon if you want to.
Plates look uncomfortable, but aren't. If it is a concern, look at the Halcyon Infinity system.
As well as Halcyon, I'd look at DSS and Oxycheq as well.