Certainly, the trip was intended to be of more benefit to Stafford-Clark, since Rogers had already written his play.
But having actually met people who had experienced the genocide, did he worry about his own approach to the story, in which the lead characters are white rather than black, and which is arguably more concerned with white guilt than with black suffering?
"I did lose sleep over this," he admits. "But if I've done my work correctly then people will find that the Rwandan characters are in some ways more interesting than the white characters.
"Secondly, I thought it theatrically inappropriate and morally dubious to set the play during the genocide. There's a reason everyone gets killed off-stage in Greek tragedy, for example: it's more horrifying to imagine it.
"Thirdly, although Nick Hytner at the National picked the play up, I initially wrote it with American audiences in mind, and, to be quite honest, you're gonna have a problem if you go to theatres and say: 'I've got this play about the incredible intricacies of a certain situation in a small African country.'
"I needed a character audiences could embrace and a structure they could relate to."
His play deliberately doesn't take sides. "When I go to the theatre in the US, I hear one voice - what you would call that of your typical Guardian reader," he says.
"But I want plays that put forward different views. Otherwise, what is the theatre for?'
The Overwhelming opens tomorrow, in rep until Aug 8, Cottesloe, National Theatre, South Bank SE1, tomorrow 7pm, otherwise 7.30pm, mats 2.30pm, £10 to £28. Tel: 020 7452 3000. www.nationaltheatre.org.uk Tube: Waterloo/Embankment