LBM Xyston decals adorn my Magister Militum Hoplites, Hypaspists and others. Only problem is where shield curvature causes the edges of the shield to ruck up but a few we’ll placed cuts deal with that. However, no slicing up - a round Hoplon is a round Hoplon.
That said - I did slice up a large Roman sheild decal to to use a boar design on the round Velite shields. I even overpainted the decal where the slicing lost detail that I wanted to recover. No snags!