I think one of the things that really might prevent me from taking salamanders is the darn template! It slows the game down a good bit and I can't imagine doing three of them for one unit.
However, based on what people are reporting, they seem to be a good deal more effective than the razordons when game-time rolls around. Plus lizardmen already have lots of projectile attacks. Sure, they're strength 3 but they're also poisoned. Str 4 offers basically the same thing, and isn't different enough to justify taking those guys. Sure they're great against fast cav, but so are blowpipes. Skirmisher skinks can get the job done just as well, as can dropped rocks and terradon fire, as well as the giant blowpipes. The only reason to take these instead is to protect your flank from charges. I suppose these might work better as flank defenders of a fast moving force.
Salamanders bring to the table the flame template and armor piercing goodness. They are basically slightly less powerful versions of the stone thrower except they are mobile and much more reliable (and you can have 3 to a group). They help bust up those static CR armored blocks that tend to give our powerful strikers trouble.
A question to salamander users... do you determine the total number of hits first, placing the template for all 3 salamanders before any casualties are removed? Or do you fire one, remove casualties and clean the unit up, then place the next template?