They should all be the same,  try it check the caliper doesn't rub on the disk on the very outter edge,  or sit to far above.

there are differences with mounts, avid and hayes will work with each other's brackets, but shimano and those aren't interchangeable,as for formula I dunno, but mine looks different again to all of those above, so may be interchangeable with shim. or avid/hayes.

The thing is the position of the piston and geometry of the caliper, avid pistons are off towards one end of the bracket and shimano are central, formula are central but the slot for the disc appears to be at a different angle to the shimano, the bracket looks dead weird when fitted to the fork/frame and I had to double check it wasn't upside down! The caliper is in a whole different position to the shimano, so I doubt it will work.

You're only gonna lose £3/4 to find out though, unless you already have one, then give it a go!

The mounts will almost definitly not work, I had a similar problem with my new formula the one brakes, I managed to get the correct mount from uk bike store, http://www.ukbikestore.co.uk they didn't have them listed on the website but after emailing them they told me they have them in stock and a day later it turned up cost me £10, they seem to be the best place for formula spares, I should be on commision or something......

Sounds like either pad contamination or, more likely, an alignment issue.  Is there any vibration with the noise?

Could probably also do with a bleed on the front at least.