Advice sought: should I use a pen name for this particular new genre?

I know it's fairly obvious that if you switch genres from, say, blood-curdling horror to romance, it's wise to use another name for the new genre. But my current WIP is a psychological suspense thriller, about an emotionally repressed doctor in a small English town who rescues a stranger from an assault one night, and then finds him insinuating himself into her life in a sinister manner.

Now, my usual genre is action thrillers. I'm doing okay with my books, coming close to earning a living from them that's equivalent to what I earn in my day job, and I have a loyal fan base which, judging by the names on my mailing list and the emails I get, appears to be around two-thirds female.

I'm fairly confident I could launch the new book with a big boost from my established readership. But I could probably do that anyway if I used a completely different pen name and told my mailing list about it. However, I anticipate that if the new novel attracts a whole new group of admirers, I could have a fair amount of blowback to my existing books - they're violent thrillers, but they all contain elements of suspense and mystery.

So, my question is: should I publish the new, quieter thriller under a completely different pen name? Should I release it under my real name? Or - and I'm leaning towards this - should I use the sort-of pen name T G Stevens, which makes my gender uncertain at first, and then link back to my usual name (Tim Stevens) and include the new book on my main author page?

I'd be interested in other people's thoughts, especially if you've been in a similar situation.

Thanks