I know this thread is old, but I couldn't agree more about Slicydrummer and Fill-in drummer especially. There are several reasons why it was so great and nothing I've found replaces it.
1.  You told it what measure number you wanted the fill to be in and programmed your drum pattern leaving where you wanted the fill to be blank, then set up a loop in Sonar and just start auditioning fills until you found the one you liked.
2.  The fills where arranged in folders by type and complexity (there were TONS of them) and whether the fill was at the beginning of the measure, the end of the measure, or the whole measure.
3. The fills were excellent and inventive and definitely sounded programmed by a real drummer or at least someone with a clear knowledge of how a real drummer approaches fills...such as having hi-hats and other cymbals incorporated into the fills and having various velocities on the notes just like a real player would.
 
Yes, the interface looked like a kid designed it, but who cares...it WORKED WELL, and enabled you to have very original and interesting fills quickly right in the places you wanted them.  I have NO IDEA why Musilab stopped supporting it and went to making guitar plugins exclusively???  WTH???
 
If anyone knows of an alternative for 64 bit or a way to get it to work in a 64 bit DAW I would love to hear it...???

EZ Player Pro might be promising, but I'm not seeing where you can audition fills in a specific measure in your arrangement like Fill-in Drummer could...that was the best feature of it!  Can anyone comment on their experiences with EZ Player Pro?
 

The ability to 'audition' fills at the beginning/middle/full/end of a measure of my choice would be phenomenal! 
 
That's stuff I only dreamed of. There was a program that did this? Man did I miss out!

Yes Grem, it was fabulous...it makes absolutely no sense to me why Musiclab didn't keep with it or why someone else hasn't picked up the gauntlet and released something that does this. It was so easy to get interesting musical fills and now it's completely tedious...lame.
 
BTW...EZPlayer Pro doesn't do anything even remotely close to what you could do in Fill-In Drummer.
 
The old Fill-in drummer works perfectly even though it's very old...it just needs to be updated to work as a midi plugin in 64 bit or some other method or wrapper to get it to work in 64bit.  I've tried the mfx.dll wrapper that has been floating around for a few years but it doesn't work...

Found the Drumtools DEMO...doesn't work right. DAMMIT!  It was so much simpler and easier to work with it as a midi plugin instead of inserting it as a vst and then trying to get it to work correctly...plus it's the demo so it's gonna expire and Musiclab doesn't respond to any questions about it.  Nice job Musiclab.