James Walterswrote a review of Sidi Frost Gore-Tex Cycling Shoe - Men's on March 30, 2019
Familiarity: I've put it through the wringer
I use a cross bike during the winter for training and I have been riding them for the last 5 months. I got these shoes to replace a 15 year pair of Sidi winter shoes that finally wore out the treads. The are a noticeable upgrade in terms of fit and feel from the prior model.
I typically will ride 2-3 hours in temps spanning 25-50 F. I will add toe covers rather than a heavy wool sock below 35 F as the tips of my toes will start to get cold after a while. As a note the covers still leaves the treads exposed for good traction when walking. For a ride under an hour, I probably would not bother with the covers. I did ride these through light rain a few times and the shoes repel water but the top cannot really seal so eventually water will work down without a gaiter.
I wear a 44 in normal Sidi road shoes and based on other reviews I got this size. For any normal mid-weight winter sock it was a nice fit. For warmer temps in the mid to upper 40s, I would switch to a summer sock and there is a bit of movement near the heal when walking but not when riding. If I were doing a lot of dismounts and run/hike that might get annoying. You can wear a heavy winter sock and still have these fit without feeling too constricting but I found the cover to be better option when it is colder.
In the end, after 5 months the shoes look new still and the construction appears good. For my use case, they work well and the only minor complaint I have is the inability to replace the treads. Assuming another 15 years of use, I think the price is justifiable.