I have a Mountaineer I, and I think it's a great knife. It's small enough to always be handy, but durable and well engineered enough to offer performance that belies its size. The handle feels a bit small sometimes, but only when using it at "weird" positions. Any other general use it fills the hand well, and the knurling offers a great grip. The steel takes and holds a very nice edge, and has proven so far quite corrosion resistant. The leather sheath is sturdy and well made, and though it seems a bit looser in its retention now after 6 or 7 years, it does still hold the knife well. The handle cavity on the smaller Mountaineer seems a bit small to fit a sufficient quantity of very useful stuff for outdoor situations, so if you're planning on stuffing the handle with goodies, you may want to opt for the larger model.
I haven't had an opportunity to handle a Mountaineer II, so I really can't comment on its feel or performance, only to say that it's a Reeve, so its high quality and performance should be without doubt.
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Don LeHue
Rome did not create a great empire by having meetings...they did it by killing all those who opposed them.