sdecker - I don't have those models to inform any opinions. But I am messing with the CS1.5 and 1.6, which exhibit similar baffle differences. The 1.5's grille board mates with the baffle to form a flush surface with 1" radiused round-overs. The 1.6 has much larger round-overs outside of a shallow (1/8" - 3mm) pocket which holds the metal grille panel with cloth over it. I believe the 2.4 and 2.7 are like the 1.6. Within all those variables, I have isolated a sonic and measured glitch caused by that grille 1.6 pocket, either the edge of the metal panel or the edges of the pocket with the grille off. Filling that pocket with 1/8" F11 wool felt eliminates the glitch and the speaker sounds larger, the image lifts and comes out of the box. With the felt in place, the treble balance sounds right without the attenuation of the fabric. The grille magnets work through the felt for protection when needed.
This discussion segues into the grille cloth thing. A manufacturer must decide how to present its products to market, and Thiel chose wood cabinets with fabric grilles, for better and worse. Reticulated foam (model 01, and a Wilson special order) is more transparent, but not very cool-looking imho. Our fabrics got more and more sheer as they became available, but it is still there as Andy mentioned. I believe most audiophiles would prefer no fabric. In fact Thiel offered grille frames with no fabric and extra finishing to match the baffle. Nice, direct sound, but with more high-end sizzle. We could have, but chose not to modify the XO to knock down the treble. A hot-rod shop such as Thiel Renaissance could offer such mods to make the purist happier. I am presently experimenting with solutions that optimize sound quality and aren't physically objectionable.
This discussion segues into the grille cloth thing. A manufacturer must decide how to present its products to market, and Thiel chose wood cabinets with fabric grilles, for better and worse. Reticulated foam (model 01, and a Wilson special order) is more transparent, but not very cool-looking imho. Our fabrics got more and more sheer as they became available, but it is still there as Andy mentioned. I believe most audiophiles would prefer no fabric. In fact Thiel offered grille frames with no fabric and extra finishing to match the baffle. Nice, direct sound, but with more high-end sizzle. We could have, but chose not to modify the XO to knock down the treble. A hot-rod shop such as Thiel Renaissance could offer such mods to make the purist happier. I am presently experimenting with solutions that optimize sound quality and aren't physically objectionable.