I was talking at the guy who was putting 2 heavy flamers on his speeder, not the guy putting typhoons on his speeder. What happens when you run into armor
Typhoons I have said are ok, depending on what else is in your army.
With multi-melta and heavy flamer I don't really see how you can not get within 12" of the enemy. If you are going to attack something, you have to go close to it. The only time you then aren't close to other stuff is if that unit was all by itself and you wipe it out.
I think it's an unreasonable assumption that you must have screwed up if bad stuff happens. Instead, maybe you have an opponent who knows what they are doing or the dice mis-behave.
The ability to move 24" has nothing to do with it. You can spend a turn running away if you like, but then you don't shoot anything. You still have to go close to actually take part in the game. That means another turn when you do nothing, and the typhoon sends off another couple of missiles.
If you'll notice I said the only time you should be getting within rapid fire range is if you want to
. If you end up in rapid fire range without planning to be there and your game suffers because of this, it's not the speeder's fault it's your fault for planning your turns incorrectly (for the most part). I don't think it's unreasonable to assume that you're a competent player. You may have an opponent who knows what they're doing but again that's not a problem with the speeder it's a problem with you, the player. And dice....well, there's nothing you can do about that. Dice affect both speeder variants, as does opponent's skill level so that's kind of a moot point when it comes to comparing speeder variants.
More often than not, you can stay at 24 with the multimelta and hit stuff. Rhinos are not really worth getting 12" away from for melta range, and neither are things like wave serpents or falcons. Yes it's more effective at 12", but don't forget you have a S8 weapon that is still AP1 (the most important thing) at 24" or an effective 36" with movement.
All I'm trying to say is that with smart movement and deployment it becomes possible to have land speeders with multimeltas fill a niche in your army that would go unfilled otherwise. Typhoons do a job that is also done to some extent by predators or dreads with long range weapons. The fast vehicle mounted multimelta is so unbelievably good when used properly. Unlike attack bikes with multimeltas, they don't go pop as soon as they get hit by a lascannon, and they can deep strike if things are too hairy on first turn.
Again, it depends on what else you have in your army. No dreads or preds? Sure, take typhoons. You only have 5 meltas? Take more melta speeders.