Definitely try before buying, especially if you plan to put aftermarket footbeds with increased arch support and varus / valgus wedges. Most of the good Giro shoes comes with a “supernatural” footbed designed by Retul with a arch support system, but those don’t suit everyone
I’m a 42 in most shoes (shimano/specialized,etc.), and probably need the 42 EV (extra volume) of Giro to accommodate the decrease in volume with putting these extra elements inside the shoe (this just pushed my feet up into the top where I could feel the straps as there is little padding under the tongue)
I could not find any EV shoes to try at retailers, and the 43 was too large