Don't despair. Your experience thus far is identical to mine.
I agree w/previous poster RE issues that would be deal killers. Except that I think a little heel lift may occur when new.
You've bought a serious pair of boots and they need serious break in. As long as you have room the toe box and they generally feel good, you're probably fine. Your situation does illustrate the value of a good fitter, like Lathrop because you may never find out if they will work for you since you may be too afraid to actually put real miles on them (and risk "owning them") and thus may return them. Don't take this as an insult, because I ended up in the same position. Like you, mine felt generally good. I kept mine, broke them in and love them.
These are STIFF boots and need a lot of miles to break them in. As I've stated in prior posts, I highly recommend getting them good and wet on the outside at least once while hiking to help the leather find a crease. I have found with Lowas that it's not a bad idea to go up 1/2 size (at least for my foot). I virtually guarantee that you will not break these boots in on a treadmill. Or.. by the time you do, they will clearly be used since all the leather under all the lacing areas will show shine/wear.
A little heel slip may not be unusual when new-- the sole, upper and rand are so stiff that there is no flex in the ankle or forefoot area yet-- so your heel may lift some. Also, the uppers are so stiff that the laces won't snug up perfectly to lock in your heel until the boot breaks in a little. I had a slight heel lift issue with my Tibets, once the sole, rand and uppers broke in I was able to start using the lacing system more effectively so it locked the heel better and better. Perfect now. I also recommend good insoles, stock ones suck. Fantastic boots.
If they feel good now, go for it.
