So I recently picked up a pair of size 42 Spantiks, same as my Evos. Initial impression with the same mountaineering sock is that the Evo's fit like a glove, the Spantiks feel a touch shorter and narrower in the toes. Don't know why but first impressions are usually spot on for me no matter how much you play with them.

I've molded the Spantiks this morning to see how much of a difference that will make. I'll give them a bit and go back to them in an hour or so. I'm hoping the heat molding will be just enough as I bought them off of Ebay and it will be hard to return them for incorrect fit. I do tend to wear my boots tight though, even my everyday yard boots.

I have left the original footbed in them as well. I'm really feeling like a 42.5 with a better footbed would probably be spot on. What have you guys found that own both pairs of these? I was hoping to keep the heavy mountaineering sock but maybe I'll need to adjust those to make these work. I think I'm dealing with a 1/4-1/2 size here. I know, I'm being overly anal

I wore the Evos on Orizaba with the heavy sock and never even thought about my feet being cold. Granted that was a one day climb and not a week long expedition. I guess worse case scenario is I have to order some 42.5's and try them on side by each. Return as required, if possible. I live in WI and there isn't a pair of Spantiks anywhere to be found in the whole state. Hence having to order them.

Thanks for the input.

edit:

forgot to ask about heel slip. For me it seems like the Spantiks have some. Any tips on trying to alleviate that? Or is it "normal" to have some in a double boot? Sorry for the newb questions.

Boot fitting online is the devil.
I, too, have to do all my high-end ordering online, and have had a lot of issues with fit, even amongst the same brand, and even within the same line! It's like a production run from Factory A and Factory B aren't always the same.
One thing I noticed is that one of my feet is 1/2 size larger than the other foot. Almost everybody is like that. But if you measure a different foot each time then you'll get inconsistent results. Figure out which one is larger and always try that one on with your thickest planned sock.
Currently I use a thick sock on my right foot and a thinner sock on my left foot in my EVOs. Might work for you.

Alternative might be to go to a ski boot fitter (or custom bootmaker, there probably are some in WI, although they're likely hunting oriented) and ask them to either stretch your liner a bit where needed, or to stretch your boot. If done properly and slowly, it shouldn't affect the waterproofness of the boots.

Check out this link of a lady with some serious problem feet. If they can fix something like that, I'm sure they can handle your issue!
http://www.backpacker.com/fit-problem-feet-in-hiking-boots/gear/17250

Thanks.... and holy crap are those feet ugly!

For now I'm gonna try a pair of 42.5's and see how it goes. I have a feeling once those get here and I play around with them a bit they will work. Worse case is I have to include a liner sock in one boot.

I wear 42.5 spantiks w original liner and custom footbed. Denali (2), Aconcagua, Vinson etc. no problem with cold! FWIW. SCOTT

Thanks Scott. I'm hoping they show up today or tomorrow and that I can get out in the new snow it's dumping on us right now.

Those summits are on my hit list and I was hoping these boots will take me there. I'm kind of getting a late start on this mountaineering thing but I'm hoping to tackle those in the next 1-3 years. Getting a proper fitting pair of boots may take a month or 2 but will be well worth it in the long run.

Strike 2 on the fit..... I'm bout ready to give up. I guess I'll try a size 43 as the 42.5's felt just as tight/short as the 42's. Uhhgg.

I'm now on the 3rd pair but these look like they'll work. I'm a 42 in the Evo's with same sock and foot bed but a 43 in the Spantiks Guess it doesn't matter, just as long as I can get them to fit. Initially I feel I may have to do something to stop a wee bit of heel lift in the 43's. But that shouldn't be too hard.