I struggled for a long time trying to decide between a L and an XL Signet-Q. The L and XL are two different shell sizes, so the size difference feels enormous between the two.
In the end, I went with the L and bought the slightly thinner comfort liner (5mm vs. the stock 7mm). I would've needed thicker cheekpads if I'd gone with the XL, and I hated the fishbowl effect of the XL helmet over my otherwise L-sized body.
YMMV, but helmets loosen up quite a bit with regular use, so I'd go with the one that's slightly uncomfortable now.
In the end, I went with the L and bought the slightly thinner comfort liner (5mm vs. the stock 7mm). I would've needed thicker cheekpads if I'd gone with the XL, and I hated the fishbowl effect of the XL helmet over my otherwise L-sized body.
YMMV, but helmets loosen up quite a bit with regular use, so I'd go with the one that's slightly uncomfortable now.