I let my homie try on my size 10s the other day just to prove to him that they're the most comfy sneakers ever and he was converted instantly even though he wears a size 11. Sizing down a little will be snug for sure but it's not like they're gonna hurt your feet and they'll stretch out a bit if you wear them for a few days in a row.
Wearing without socks or w/ no show socks & a smaller size might be an issue due to size tag on the inside of the tongue, if the tag makes direct contact with your skin and the shoes are really tight, it can irritate it a bit.