Your ass, my arse?

I asked this question of a bunch of my fellow erotica authors recently:

Here's my dilemma...

When I'm writing about anal sex, or even just that part of the body, what do I call it?

I'm British and my stories are usually set in Britain with British characters. So we call it an arse, not an ass. It just looks wrong to write 'ass', for me, and it would be out of character in my stories. Butt is very American too.

But my largest audience is in the US, so does it jar for American readers to come across the occasional arse, so to speak?

And I know it messes up my SEO: all those people searching for ass sex and butt sex won't find my very British arse.

What do other Brits do?

The answers came down very firmly on your ass, rather than my arse. Americans find English words intrusive and likely to break the moment. They'll even give up on a story altogether if it's too English. We Brits, on the other hand, are accustomed to reading American literature, so it's less likely to break the spell.

But what do I do as a writer? Most of my stories feature British characters in British settings, and I still find it difficult to have them say ass or even to use the word in descriptions. But now I'm wary of using my arse for fear it might put people off.

I'd love to know what readers think: do you find my arse off-putting? Do you prefer ass? Does it even matter, as long as the story is well written and horny?