Not personally, but I do know one of their UK display pilots and spoke to the manufacturer at the main trade show last year. The biggest point that they make and it applies to your cowling constraint, is that these are still aircooled engines. Just because they are slimline and can fit inside a Spitfire or Mustang cowl does not mean they will run that way. They still need a big airflow over them to keep cool. If you can arrange for ducting or whatever to ensure unrestricted airflow just as you would for any other engine then you should be ok.

Harry