Hi cayo 2 & treewell, hope you're ok.
About Greg I've been in contact with him trough email many times. The info he has at his website is awesome. About the river of the photo, this is the Lower Suchiapa. The rapid is below a bridge heading to Tuxtla Airport and is the only rapid on the place, perfect as a playspot. Im a rookie playboater and since there's no kayakers here it's been kinda difficult to dare to paddle the rapid by my own (specially the center part where the biggest hole is located). About Tapachula I've paddle twice the Coatan and I'm waiting for a chance to go to Cuilco, Cahoacan ando Novillero (these are mentioned on Greg's site) with a rafter friend from the south.
A nice creeking river is the Santo Domingo but this is really too extreme for me (look for some info at youtube searching a video called POV waterfall). I met a group who made it on april this year. About the other rivers you mentioned, I would like to go but don't have a support team to go with me and don't want to kayak alone so if you ever come back to Chiapas send me an email ([email protected]
) and we'll see which places we can visit.