I haven't had any concerns with it nor have I "pampered" it since they replaced it. Leatherman stands behind their products 100% - lightweight, smooth-action, and the one-hand quick-flick knife - btw I noticed it is priced below $40?! sheesh. what's not to like?
I ran a web search for images of both, and it appears the Leatherman 830850 is dark grey metal with carbon fiber inserts/components (this is the one I own) whereas the 830846 appears to be all metal (silver stainless steel). From what I can tell, the difference is only aesthetic. Also, in regards to the comment below, I am not sure they are continuing to manufacture the 830850 with the serrated blade. When I purchased mine about 6 years back, it came with the serrated blade. However, after some issues which required me sending it in for warranty (they've got a great warranty, that I must say), they sent a refurbished (practically new) skeletool with the straight blade. On their warranty page there is a disclaimer saying that for this model in particular, they no longer provide the serrated blade, and may replace the blade with a straight one (which is what they did with mine). Depending on if the vendor is selling a recent batch or an older version they had in stock, I would guess you might get either serrated or plain edge.
As long as you put it in your checked luggage and not in your carry-on or on your person, you should have no problem. Declare it in customs just in case, but most airports don't require that you declare knives on your checked luggage- only firearms. Hope this helps.