I can vouch for the FORA .049. I flew it 95% of the time in RC speed planes and never had the head or backplate off of it. Very easy to needle on bladder and ran well on 15%. I gave it away after running it for 7 years and got a Cyclon .061. It has the same basic level of performance, but more expensive. I can't say much about the Profi except if Jim Booker is backing it, they must be high quality. These engines will tend to turn 1/2A RC combat into a miniature form of demolition derby though . I fooled around with some 75% "scale" SSC planes [about 48 inch span] and my Fora .049 and came away with the impression that it was pretty nuts.
The main thing to keep the action at any level tight and close enough to avoid mid airs is to keep the speed and weight down, keep the planes even in performance and encourage the pilots to stay within a tight box to discourage the high speed runs that tend to reduce the outcome of that moment in time to a coin toss.