Randy,
I think it comes down to two things...
do you enjoy 'rolling your own' over buying something?
-and-
do you want or need complete control?
I like scripting, I spent a large part of my career writing shell and PERL scripts to do tasks, the concept just makes sense to me. Some call it the "tool builder" mindset that permeates the unix world<G>!
But, I have grown a bit weary of having to write scripts to accomplish things in the studio. That, and CAL is starting to get a little long in the tooth. If a more modern scripting language were adopted I'd give it a whirl, no question, but at this point I am looking for tools that other folks have built, and Franks Plug-ins are once again on my radar.
I don't think that they do anything that can't be done in CAL, which is why I never got around to purchasing them in the past. But Jeff's points are all valid.
Getting back to the OP - my favorite tools for humanizing drum tracks for a very long time were Slicy Drummer and Fill-in Drummer from MusicLab. I'd write my own patterns, and then let these two plugins vary the velocity and timing for me, and dang, but the end result was always very musical.
Over the last 12-18 months I've started using Jamstix a lot more for this application. When I first got Jamstix (v1) I let it create the patterns, and sometimes it worked and sometimes it did not - in the context of the composition. Over time I got more adept at adjusting the settings to satisfy my tastes.
Then I discovered that I could let it process my patterns. That's when I switched from the MusicLab plug-ins<G>! Now Jamstix is a DEEP program, and I'm still learning new things about it (haven't upgraded to 3 yet because I'm still wrestling with 2).
And of course it does quite a bit more than the MusicLab plug-ins which is both a good thing and a bad thing.
I'd have to recommend both MusicLab and Rayzoon as viable solutions to humanize drum parts. Perhaps I'll add Frank's plug-in suite after I've given it a fair trial...