Personally, I would opt for the Saito. Just finishing up a Hangar 9 Christen Eagle and I had choices between, DLE-20, OS GT 22 and Saito 125. I opted for the Saito.
Just wondering how you will be mounting the engine, sideways or inverted ? Only reason I ask is that perhaps some of the cowling trimming could be avoided. I know that they are different, but the Saito in my Eagle fits completely inside the cowling with no trimming. Only hole I had to cut was for the needle valve. I also mounted a remote glow starter, thus also saving another hole from being drilled to access the glow plug.