I am not a Tech diver, apparently I don't do anything right, and I don't pretend to be any kind of expert. However, you sound like I was a few years ago so I will tell you my opinions (but only because you asked).
I suggest that you keep things simple in the beginning. I started off by getting simple gear similar to what I was certified using. I did not want to make things overly complicated at the outset. Over time I learned more, and then I was in a better position to make informed decisions about what to do or buy. You can always add more gear and more complexity later.
Some people know exactly what they want from the beginning, and that's great. Others of us want to learn and grow and have some fun. I wanted to keep things simple at first and just learn to be comfortable in the water, and to focus my attention on diving and diving skills.
My buddy is a gadget freak, so he has to have every doodad and gizmo in the world. It took a while before he was able to utilize everything he carried with him. Of course that is just his way, and there is nothing wrong with that.
If you are handy, you could have an octo for traveling, and you could remove it from the first stage and plug the hole whenever you choose to switch. Personally I think that there is value in keeping your gear configuration as (relatively) consistent as possible so that you know immediately where everything is regardless of where you are diving.
Remember that just because you have a Pony it doesn't mean that you can't also have an Octo. Some would crucify me for heresy suggesting extraneous gear on your body, but it is ultimately your decision. I would have the standard set up and add the Pony as an addition whenever the circumstances warranted it, but that is just me.
Of course I have an Air2 on my BC and there are those that would shun me for such a configuration.
Sorry for the rambling. I had some points in my mind, I just hope they didn't get lost between there and the finger tips.
Wristshot