When i first got them i wasn't that impressed but now i couldn't do without the Metal pack.
Like Chris said,the FX Junkie is not so hot but it comes 'free' with the Metal Pack anyway.
At least when you've got the extra amps you aren't constantly wondering if you really should have them.
It took me a while to get the best from my XT but lately i've been getting some brutal sounds from it.I found that it sounds hugely different with different pickups feeding it too.