Reverse Thruster: Gives you the ability to fly backwards. I’ve always found reverse thrust to be a waste of a perk. I’d rather be able to kill people more efficiently than be able to fly backwards, and since explodet has the ability to escape stall death with mines reverse thrust seems less useful. Note that your mines and rockets act strangely while reversing. If you really want to fly backwards use this perk.
Mine hopping takes energy and damages you slightly, reverse (these days) takes basically 0 energy and doesn't damage you.
~ Allows you to easily choke up small, tight areas with many mines in ways non-reversers can't.
~ Allows you to easily rain down rocket death to those below you. Valuable for defense on pushes from below on maps like middleground and mayhem.
~ Allows you to do a full retreat while firing projectiles forward, since fatty rockets constantly accelerate and quickly get over your backwards momentum.
~ Using reverse allows you to escape far more situations than just stall death.
~ Bombs are much easier to block with reverse fatty.
~ Makes it much easier to respond to someone bomb-rushing your base, even if you're a decent distance away.
Reverse-rocket quirkiness is very awkward and hard to come to terms with, but like most other skills in alty it will eventually become like second nature to you if you practice it enough. I don't consider myself as having come anywhere close to 'mastering' this, but on many occasions I can fire a rocket off while doing a 360-reverse-loop, have the rocket curve in a weird angle, and have it smack right into the nose of a bomb carrier who wasn't even on the screen when I started dancing about. What's important to grasp is that even though the rocket goes through an initial curve or whatnot, the acceleration eventually makes it go in a straight line, even if the rocket is pointing in an odd direction; I've often had rockets pointing at a 45-deg angle move along the horizontal plane. These days I kind of feel like using reverse-spin-rockets is like throwing a ball and chain, except the ball is a ... rocket? It's hard to explain.
All in all, though, I'd have to agree with the sentiment that reverse on a fatty is more defensive in nature than it is offensive.