Depends on where you play and who you play with.
GW store or official event: obviously no
Non-GW event: check with event organizers in advance for official answers.
Independent location, gaming with friends: probably fine, but you should talk to the club/friends directly to see what they think.
Independent location, gaming with strangers: probably fine, better if you converted wings, but you'll need to clear it with each opponent before gaming to make sure they're cool with it, and have a variant list prepared in case they aren't.