Hi all, first time post!

I've been building, gradually, my touring/commuter bike for the past 5 years as I learn new things. Recently I wanted to upgrade my bartape, going for a vintage look by using cloth bartape on top of the more cushiony stuff you can buy these days. I ended up removing this second layer because (1) it wasn't the best color choice, and (2) I thought about how tedious it would be to change brake and bar-end shifter housing. Then I thought, if removing bartape twice is such a chore, why put up with removing it once? And, if you are replacing bartape, the housings can become a factor when you're re-wrapping. So then I thought, internal cable routing.

There are horror stories around internal routing, specifically as they run through frames. It's difficult to replace things, and it can cause structural problems whether you hack the frame or it was designed that way. But for handlebars alone, I feel that's not such an issue: the housing is traveling along basically the same curvy path it would have outside the handlebars and under the bar tape, and they use the same amount of housing either way, so friction is not really an added problem. There are also techniques to reduce the frustrations of replacing cables/housing when internally routed, and I would think that whatever inconvenience this method has should be compared to the inconvenience of redoing bartape each time. I might be missing something (please share what you know!) but most discussions around this topic focus on internal routing through frames and I think handlebars alone can have a different set of problems and opportunities.

Which leads to some questions:

• on average, how much time is saved by bypassing bartape with internal cables, while dealing with the added challenge of replacing these internal cables -- versus external setup?
• can I drill old-school aluminum handlebars for this purpose? If I did this hack technique, are there ways of reinforcing the holes, and to cut them in such a way to make replacing housing/cables easier?
• if NO HACKS, what purpose-made handlebars on the market for touring would you recommend?
• the technique for replacing internally-routed cables/housing seems like, you remove the housing first, then add the new housing, then remove the old cable, then add the new cable. It's not as clean an install as if you replaced both pieces at once. How much chance is there for residual rust/debris from transferring from the old parts to the new? Is it better to replace the housing first, or the cable? What precautions could I take?
• aside from ease of mechanics/aerodynamics (hah, on a touring bike), are there any significant advantages/drawbacks to using external/internal cable routing?

My mindset, if you might guess, is to go for this challenge/expense in order to get long-term maintenance returns. But if the community here has opinions that this makes no sense, I am as I said ready to learn.

Apologize if this is I just want my steed to be fast, sturdy, maintainable, and looking a bit sharp.