I don’t do anything fancy to mount spiral blades. Just put ‘‘em in. Does your saw use a special kind of clamp? I have used them in a DW788, Excalibur, and Pegas clamp heads.
I don’t know if it makes any difference in the Dewalt. The Excalibur 21 Manufactured in Taiwan was said to be better than the one made in China. The Dewalt I just purchased from Amazon was made in Taiwan.
When using flat blades, the vinyl glues back together behind the blade. I might be doing something wrong. I just use spiral and I don’t have the issue.