Ironically the very last thing I cut with my Mk3 WAS an onion. How did you know that????
I do think the S30V keeps an edge much longer than the lower end steel knives I've owned in the past (a Buck folder and a Buck Special - the Special never took a good edge). I tend to prefer stainless steel because I don't have to worry if gunk doesn't get cleaned off for a few days, though even stainless will corrode (my original Boy Scout knife from which I was a kid has corroded because at some point I didn't clean off the can opener). Beyond that I'll point you to this Steel FAQ and a review in BladeForums:
http://www.bladeforums.com/forums/showthread.php?t=368828 http://www.bladeforums.com/forums/showthread.php?s=&postid=1660197#post1660197The Mk3 with a 0.14" thick blade and high grind will slice onions very well AND is tough enough to take reasonable abuse. It is not built to chop down 8" trees, though I suppose it could be done. It is not designed to batton 8" logs. If you use it to try to pry open a car door, it probably will be damaged. That does not mean it isn't a really tough knife.
If you haven't read Doug's description of the Mk3, you'll find it here:
http://www.equipped.org/rsk_mk3.htmI don't have multiple kits. I think of mine as being nested. I have a fanny pack that fits inside a daypack that fits inside a duffle. For larger camp items I keep them in plastic tubs that can quickly be loaded into a truck or trailer. I only need one of each expensive item, though I do EDC key items in pockets. So, I only need one good fixed blade knife.
If you are looking for good lower cost fixed blades take a look at the Becker BK10 Crewman with a 0.188" thick blade for about $55. A great heavy blade for the price, but I find mine a bit too thick for a general purpose camp knife. Some complain about its handle size/smoothnes, but I actually like it very much.
If you want even lower cost knives, then look at
http://www.ragweedforge.com/SwedishKnifeCatalog.html. The #711, #746, #731, #748, and #749 are great knives in both carbon steel and stainless for under $20 each, though their 0.098" thick blades aren't heavy blades like the Beckers (0.188" thick). The #2000 is also popular, though a bit more expensive $30.
My story, as I've said elsewhere in this forum, is that I first bought the Becker BK10 Crewman but found it too big for a camp knife. I'd heard Doug was coming out with a fixed blade and REALLY liked his folders so I decided to wait. In the mean time I bought two Mora knives - a #746 and a #749 - to tide me by.
Now that I have the Mk3 I am very glad I waited and do think it was worth the cost. I have no plans to buy another fixed blade. The Mora are now stowed in my popup camper and do very nicely as sheathed kitchen knives.