Lastly, as evidenced by the 'How many regs do you own?' thread, most people (who progress to doubles) wind up with more than two regs (regarding converting Tek3s to single tank use) although I do agree versatility & exchangability are things to be considered when choosing regs
Actually I have about 18 - with about double that in the garage and don't have any rigged as single tank set ups (if I want to look at fish I'm pretty handy with a wrench). I was referring to stage use which I was guessing that the OP was progressing towards if he was moving to diving doubles.
When technical diving, you may be asked to lend a post to a team member on a project, you may have to rig a back gas reg as an argon reg, you may have to convert all your back gas regs to stage regs or vice versa. It happens (all of the above have happened to me). I can see what the Tec 3s are trying to do but I think the loss of flexibility is a big price to pay for some slightly less convenient hose routing.
You reach a stage eventually that your back gas regs are used to power your wing and that's about it. Your stage regs become much more important to you, I certainly breathe my stage regs for far more time than my back gas regs and thus I regard them as just as important (if not more so). I don't buy poor quality regs though so it's kind of immaterial.
Whilst I admire your ability to snip around my post - I would merely point out that my comment about the expense of the Tec 3s was not to compare them with Scubapro or Halcyon but to compare them with their stable mate DS4s which do just as good a job for roughly half the price (here in the UK).
I have no clue about US pricing I'm afraid but here the Halcyon and Scubapro rges are coming in at about the same as the Tec 3s. Given the flexibility and routing benefits of the others, I wouldn't buy the Tec 3's but it's your party. If you want budget regs which are still bomb proof then DS4s are great. A lot of my students start out with them due to budget but then stick with them as they perform.
Oh and to answer the why Halcyon question - I support the brand as I know that the no quibble customer service policies support me in the diving I need to do
Finally - again for the OP - I'd recommend the Evolve 60 too.