Do it!
As someone that plays Catachans, I can tell you that their benefits are many:
1) If you like the models, but don't want to get complicated with rules, play them as a regular IG army. I, for one, can't stand the uniformity of Cadians and wish the IG would branch out again with its multiple armies (i.e. Mordian, Valhallans, Tallarns, etc). So what I have done is make two army lists, one for Deathworld play and one for regular play. In this, the Catachans are pretty flexible...
2) You can play jungle Deathworld. If you host at your house, then you typically can play on your own terrain. General consensus is that the DW codex is still legit.
3) There is a paragraph in the codex that says that not all deathworlds have to be jungles. Some are barren desert or ice wastelands, some are high or low gravity, others are volcanic (like mine). This paragraph is still hotly contested, and it seems only deathworld players can come to consensus on it. Everyone else still cries unfair. Whatever you do, if making up home turf rules, be fair with it and run it by your opponent. If it mixes in with the fluff, it may go. But don't be the player that changes your army's home planet every game (This week, they're from a low gravity planet and move farther, but next week there from a hive world and treat rubble as normal terrain) Be consistent and have the fluff to back it up.
Most of all, I would say to choose based on the models. Either you like the look or you don't If you like the idea of an army that is serialized and sterilized and looks exactly alike, then go Cadians (no hard feelings, guys). But if you like the idea of an army that looks like they drop their gear whenever they get tired of carrying it and seem to have no standardization among the ranks, go for Catachans. And don't listen to anyone that says you have an army of Rambo clones... so what if you do! :rofl Every army in 40k is cloned from somewhere...
