so i just got back from the bike store and they told me my front derailleur, cassette and chain have to be replaced, dont ask why its my fault and i feel like an idiot. anyways, im wondering since i have deore components im thinking of just upgraging my whole drivetrain to xtr. if i have a 2009 rear xtr derailleur can i use it with a 2008 front derailleur? can i use a deore cassette with xtr dreailleurs? also whats the difference in the deore, deore LX and deore XT line?