I don't think the 3G price hike over VG10 is worth it. Fallkniven's VG10 with convexed edge is really one of the best 'stainless steel' options out there for combination of wear resistance and toughness, and of course corrosion resistance. It has a proven track record in every imaginable application and context, from couch warrior to multi-day backpacker to fisherman to spec ops death ninja. 3G is an improvement only in wear resistance that ranges from incremental to 'massive,' 'whole order of difference,' etc., depending on who you ask. (IMHO, those who say 'massive' have lost all sense of perspective; mostly significant for hunters in any case.) Also, the F1 3G steel is a laminate, with 3G core and softer outer steel to improve its toughness and corrosion resistance. The 3G laminate's outer layers are softer than the solid VG10 blade, which means it's a little more prone to scratching. Purely aesthetic and the sort of concern poo-pooed by "hardcore users," but FYI.
Re sheath: there was a recent, very enlightening thread on kydex vs. leather vs. Fallkniven's zytel in freezing temps. I don't have a link to the thread but it featured this video review:
http://www.youtube.com/watch?v=6LhBfUbPtfs
Of course your mileage may vary depending on your environment. There are several makers of after-market kydex and leather sheaths for Fallknivens. Knivesshipfree.com, which cutter17 recommends, is a good place to start: for leather, both the Ranger sheath and the Bushcrafter B sheath would work well.
The Fallkniven F1 is a great, even near-classic knife at this point. Whatever you decide to pick up, you won't regret it. Enjoy -- and tell us about it!