Re: HELP! Somebody, please tell me...
The consensus among most is that the only major advantage that the rolled tone hole provides is a more secure seat for the pad/tone hole rim relationship( and extends the pad's life), and some will go further and suggest that it can effect the tone and response of the horn as well.
In reality, IMHO any difference is negligible. Most manufacturers did not adopt the process, whether it was due to cost, patent infringement, lack of interest etc. is debatable. Suffice to say, no one is using this on their horns any more (I don't count the Keilwerth "rolled tone holes" as these are actually an applied ring, not a true rolled tone hole, although the purpose is the same). Additionally, some of the best horns ever made never had them.
If you are wondering whether to get the Conn 6m/10m/ horns with or without RTH: those that have them are valued as such because of their collectors worth as much as anything else. These were the Golden age "Ladyface/Nakedlady" horns of Jazz legend.
In practical terms, those horns made after this time without them were every bit as good a player, and sometimes better.
In the case of the Keilwerth, although some may disagree, I think that the added cost of the RTH is better spent elsewhere, and would go with the plain SX90 horn. Be aware that there are some other minor differnces between the two horns too, such as palmkeys etc, but nothing major. My two cents.