Can someone more familiar with these engines give me some guidance?

Are these conversions worth the trouble? Do you wind up with an engine that closely approximates the power and reliability available from DA or BME or others. Is the weight within reasonable bounds?

I'd love to do this, and would hate to spend the exorbitant amount of money I think the mfrs charge for their engines, but wouldn't want to end up with a dog of an engine......

Thanks for any info!

Joe