[Hey guys, been inactive for a long time. Came over to check on what's up with the Foundry server lag, and found this thread. Thought I'd contribute my 2c for the only clan I ever felt likeI was a part of. I still mostly play on eGO servers, as XAE.]
I grabbed the sapper and the new minigun. Both are pretty useful, situationally.
The minigun may be the cheapest weapon in the game for its role. When you appraise it, you have to ask yourself-- what role is this designed for? Huge ammo consumption, ring of fire only in melee range... Its primary function is to sit on an Engi nest, setting afire any Spy who dare come near. Disguised spies who blend into a big group of enemies near an Engi nest have the benefit of anonymity, which buys them at least a few seconds of sap spam before they get smacked/shot/forced to escape. This gun completely does away with that-- the dispenser keeps the Heavy constantly pumping fire. If you want this nest, you gotta take the heavy first.
The Huo Long is not designed with pushing as its primary function. It costs too much to fire. But for engi nest camping, only a super-vigilant pyro is a better choice. It does have a few other situations in which it is useful. If you're having trouble with a Spycicle spy, you can switch to it and (nearly) nullify the spy. In medium-sized pathways, you can cut the whole thing off from spy passage with one heavy strafing back and forth. I had this happen to me on Map 3 of Dustbowl. It was aggravating.
It should be noted that you CAN stab a fire-ringed heavy without getting lit up yourself. It takes a bit of luck or timing, since you have to stab between fire pulses, but I've managed it a couple times. Both by complete luck.
The RTR is useful in certain situations. The deconstruction timing is like this after the latest patch:
Level 3 -> Level 2: 3.0 seconds
Level 2 -> Level 1: 3.0 seconds
Level 1 -> boom: 6.0 seconds
The total destruction time of a L3 sentry is LONGER with the RTR than with the stock sapper. But if you can keep the Engi off the building for 3 seconds, you just did a few different things. First, you downgraded a building. HUGE when dealing with sentries-- a Level 2 is not nearly as intimidating as a Level 3. Second, you just cost that Engi 200 metal per stage downgraded, and the time it takes to re-upgrade. Third, you've annoyed him by costing him so much metal and time.
A few notes/caveats about the RTR. If you destroy a building, it doesn't just go boom. It reverts to a toolbox, which contains 200 metal. I'm not certain, but it may also function as an ammo/cloak refill as well. I have not tested this. Second, the time-to-destruction for a mini sentry is longer with the RTR than with the stock sapper. So much so that it's a sub-optimal choice if you're facing Gunslinger Engies, unless the Teles/Dispensers they've fully upgraded are more of an issue.
All in all, the RTR is more useful than the stock in certain situations, and the stock more useful than the RTR in others. I've noticed that if I'm very quick running around Foundry, and can get to the Engies before they get their sents upgraded, the stock would serve me better, since there is no downgrade to be done and the destruction time on a Level 1 is longer with the RTR. But if there is a mobile Engi running around even a tiny bit, playing support, the RTR is a much better choice. He doesn't have to be far off for his movements to cost him a full level on all of his buildings.