One of the reasons that you can not find a FastTracker Instrument with MIDI drums is that XI can not have more than 32 samples stored in it. MIDI uses 62 drum samples. Perhaps an ITI could have them all in it.
Another reason which may lead to the fact that you do not get the drums you want after MIDI conversion is that MIDI is only notes and the samples are stored on your audio card. That means that the samples will vary on every sound card. Though, most PCs with Windows has the GM.DLS MIDI samples.
A last reason may be that you've used the wrong method of converting the module (I assume you are converting a module since you are writing this in a tracker community) to MIDI or your MIDI conversion utility has a bug.