Not familiar with Troels subs, but have heard several of his designs, and they have always been impressive.
I have heard GR Research’s open baffle subs, and they are among the best I’ve heard. As much as I love my enclosed subs, there is nothing quite as natural as OB subs.
Nice thing is, you can get them with flat packs, so there is not cutting. Just glue 'em and screw 'em.