I have never been happy with 30p slowed down more than a little in Premiere Pro let alone 24p.
Obviously you know you can shoot 6op and play it back at 24p. But you don't want to. I just don't know why. In fact, I don't really get the attraction of 24p in the first place. I know it looks more film like when shot properly, but I don't get why that is such a desired result.
Personally I am torn between the quality of shooting 30p all I-Frame at 72Mb/s or shooting 60p but at 50Mb/s. I reallly like playing with the slow motion but I want the 30p quality. At least 30p slowed down looks better than my HDV ever did since I don't have to deal with interlacing.
But let's face it. Sometimes After Effects is the right tool for the job. Or get a Twixtor plug-in. But $595 is a LOT of money when you already have After Effects anyway.