There would be a pretty large performance difference between a DLE 20 and a YS 115. So much so that a DLE 30 would be nessesary to make up the power difference. At that point the weight of the 30 would be playing a larger factor. Of course this will all depend on expectations. The YS 91 and DLE would be on par power wise with the weight advantage going to the YS. The last 10lb airplane that I owned had a Webra 120 for power and while it flew fine, it lacked power by today's standards. The Webra spun the same 16x8 as a DLE 20. The question for me would be just how much vertical performance does the OP want?