it seems like when working on an IT project, using Gxx between instruments with different samples retriggers the notes but on an XM project 3XX never retriggers the notes even between different samples, anyway to curb this behaviour?
I am not sure what your problem is. Yes, the two formats work differently. Are you working with the IT format and want XM behaviour (hint: try the Compatible Gxx (http://wiki.openmpt.org/Manual:_Song_Properties#Compatible_Gxx) setting) or are you working with the XM format and want IT behaviour? Switching between samples using portamento is not possible in the XM format. And in the IT format it can be dangerous because OpenMPT does not fully emulate IT's behaviour there.
oh wow, i didn't realize, you're right. for some reason i thought that XM could do that but I think i was confusing different instruments with different samples. sorry, cheers! It's just the way xm doesn't change the sample when you use portamento but IT does that threw me off.
I don't know if this is helpful, but in .it, if you clear the instrument column next to the in the note next to the Gxx, it won't retrigger the instrument with a new sample.