I'd prefer a match chamber in a factory barrel as long as it feeds ok from the mag (even though I usually single load). Whether or not I'd pay someone to put a match chamber in a existing factory barrel kind of depends.Maybe so, but seams to be a market for it for, and manufacturers/ gunsmiths offer different chambers for a reason.
I have two factory rifles/barrels with match chambers that shoot really well. I have another sporter with a match chamber that shoots well but not like the first two. I have two other rifles with CIP chambers (T1X and 452 American) that shoot better than the previous one but not quite as well as the first two. I have a sixth factory rifle with a match chamber that doesn't shoot as well as any of the previously mentioned (and I still haven't figured out why, it slugs well etc). So for me a match chamber is just a small piece of the puzzle and it's not necessarily a must have when I consider purchasing a rifle
As far as paying someone to add a match chamber. I wouldn't pay anyone to rechamber the Tikka or CZ I previously mentioned. They shoot too well as is. If I was going to do anything it would be a complete rebarrel with a Shilen but that's not going to happen
I do have a 541X that I bought cheap years ago because the stock was cracked and the rear sight was missing. It didn't shoot like I hoped it would. So it sat for awhile until I finally sent it to Brian Voelker to rework. It's one of best shooters I own. However, he did a lot more to it that just rechambering it. He threaded the action and barrel, rechambered, cut muzzle on tight spot and recrowned etc