I'm also a former sequencer (MIDI-based composition), and i'm only using ModPlug Tracker until i get one of those new-fangled fancy-schmancy keyboards that has every sound you could possibly want or at least be able to create.
"Tracking," as it's called, has the advantage of being able to easily exchange, or at least upload, self-contained music, mostly because it contains the samples you need already in the file. But the disadvantage is, that many times you have to fix the sample so you can use it (unlike sequencing, whose main thrust is not in adjusting sample data). Drum loops are an example you've recently found.
There are three ways to get your drum loop to play continuously at the right rate.
1. Adjust the song tempo (either under the General tab, or by using the T effect) so that the loop finishes just as the measure ends. It usually requires trial-and-error to tweak it perfectly. The disadvantage with this method is that you cannot manipulate the loop sample except to cut it off midpoint.
2. Get the closest tempo that plays thru a measure at the same length of time as your loop, but play the loop at a different note, rather than the usual middle C (C5), maybe B4 or C#5. The disadvantage of this is that it not only changes the tempo of your loop, but it also affects the timbre of your percussion sounds within your loop -- both of which may be unacceptable to you.
3. Use a sample or wave editor to "chop up" the samples from the loop, so that you have a kick, snare, and the other percussive sounds each in its own sample, then just play each sample at its proper time in the measure of a tempo of your choosing. The disadvantage of this is that it can be time-consuming, especially if you don't know how to edit waveforms or samples. Also, it doesn't work too well if you have a continuous sound within the loop (such as a pad or sustained synth chord). But if you can use this method, an even bigger advantage is that you can reuse the percussion samples in another composition in a different rhythm.
If you're like me, when you find (or create) a great drum loop, you generally don't want to change anything about it, except maybe to add riffs. But see which way suits you best for your composition, and go with that. And as i'm sure everyone in this forum will tell you, EXPERIMENT!
