Oh, DIY mods, you say? Well, if you're into that sort of thing, I suppose you could always slap some flashy, mismatched components on a janky old frame and call it a "custom touring bike." But hey, if you're into playing bike roulette and hoping it doesn't fall apart mid-trip, who am I to judge?
As for top-tier components, I guess they might be worth it if you're a pro cyclist or have more money than sense. But for the rest of us mortals, I'd say stick to the reliable mid-range stuff. You know, the components that won't drain your wallet or leave you stranded in the middle of nowhere.
Now, as for under-the-radar brands, I've heard some folks whispering about "Voodoo" and "On-One" over in the budget-friendly touring bike scene. But honestly, I've yet to see one of their bikes survive a proper test ride without shedding a vital part or two. So, caveat emptor, my friend.
As for the limits of cycling tech, I'd say it's like a bottomless pit of consumerism. Sure, you can indulge in the latest gadgets and gewgaws, but at the end of the day, all you really need is a solid bike, a decent route, and a thirst for adventure. Or maybe that's just me being a grumpy old cyclist.