Now that's what I call a question.
I'm no expert on waders. I'm not really an expert on many things, come to think of it. But I own a few waders and I backpack to fly fishing destinations with waders. I can tell you what has worked for me.
I have a set of Dan Bailey Barebones waders:
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These are lightweight, no-frills waders which are fairly rugged. I have used them for three seasons and only this year did I notice a very small seepage from the knee seams, which I repaired with a little wader goo. They are light to pack and they stuff down to the size of a large bread loaf. They have a roomy fit, even for guys of more generous proportions like me. A thin guy will have no problem with layers. Use UnderArmor or similar longjohns and you can wade in the middle of winter (which I do with these waders). While I have seen waders that are more robust (extra fabric, double gusseting, really heavy seams, etc.), such waders are much heavier to carry. My Simms waders weigh almost twice what the Dan Baileys weigh and are bulkier. The Barebones are not convertible per se -- but you can unsnap the suspenders and tuck the upper material under the wading belt, as I have done many times.
Dan Bailey Barebones used to cost $179, now they're $149. The warranty on Dan Bailey products seems fair, but I've never had to test it -- no major failures and only a slight seepage (not even a leak, really) after heavy use over three seasons of year-round fishing.
As for boots, any namebrand wading boot will be rugged enough to hike short distances, even felt-soled boots. Your question could be interpreted to mean that you plan to hike into your destination in wading boots. That's not a good idea. Wading boots only fit right with your waders, over socks and the neoprene bootsock of the waders. They won't fit like regular hiking boots with just a pair of socks. Unless you plan to hike in wearing your waders and wading boots, you need hiking boots for the trip in. Plus, wading boots aren't made for long distances. A few miles over ordinary terrain is fine for a sturdy wading boot, but they're no replacement for hiking boots. If you hike a lot in your waders and boots, both will have a shorter life.
Yes, you can mix and match waders and boots. I happen to like Korkers, which can run you from $80 to $200. The important thing is that you try them on with your waders and the socks you'll wear. Stick with the namebrands but find the one that fits you best. Do NOT get a pair of cheapo Hodgeman or similar boots -- they suck to hike in, suck to wade in, and will come apart under heavy usage.
Having said that, I will point out that you can take a different trail, so to speak. Last time I backpacked to fly fish (to the Wind Rivers), I did not want to pack my wading boots. I was trying to get my pack nice and skinny, so I left the boots (they weight 3 pounds or more) at home and strapped a pair of Teva sandals over the wader's neoprene bootsock. This worked incredibly well. I packed my waders and Teva's in a small pack for day hikes and suited up when I got to the water. The Teva's gripped the slippery rocks and were comfortable to walk short distances. Yes, I was more careful about wading -- tried to avoid underwater snags and anything that might damage the exposed neoprene, but it didn't take much effort. Since I was going to bring the sandals anyway, I felt like I had really gotten away with something.
Brandnames. Simms is the first name in waders. They are the best. This is my opinion, but it is backed up by battalions of fly anglers and many years of reputation. Here's something else, and this is a fact -- Simms are the most expensive waders. Why are they $400? Because they're worth it. They're tough, reliable, they fit well, and hardly ever leak unless you willfully puncture them on a barbed-wire fence (and sometimes even then they won't leak). They have all kinds of funky extra fabric and stitching where it's needed most. They're actually kind of hard to damage through "normal" use. As far as I have heard, Simms are good to work with when it comes to warranty. Again, I have never had to redeem my warranty, but others I know have done it and it worked out reasonably well. Orvis? Never owned a set. I'm sure they're fine and I have not heard these stories of which you speak.
The difference in cost will, in most cases, translate to a difference in quality. Sure, you pay a ridiculous premium for the latest and greatest set of Simms -- $650 for this year's model? No thanks. But in general, you get what you pay for. A set of $99 waders WILL fail before a $500 set. You can argue if a $300 pair of Orvis waders are better than a $250 pair of Simms. However, when comparing the upper shelves to the bottom shelves it's true (though I wish it were not) -- more money means a better wader.