They're both the same guitar but with different pickups and fingerboards.

Are you willing to go used and buy something better? The older MIJ Pro series Jacksons are much higher quality than the current X series. Put a new Floyd in them and you're good to go.

What is your budget? What is your approximate location?
Roses are red
Violets are blue
Omae wa mou

Quote by Axelfox
+ 1 with above.

Also, looking at the spec's the necks are slightly dif' as well...  the MG' has oiled neck,  3-Piece Maple with Graphite Reinforcement with the XM having  Gloss / Painted , 1-Piece Maple Neck-Through-Body with Graphite Reinforcement and Scarf Joint 

Which one better? I guess it's down to spec's preference. Me, for "Old School Metal" and Rock... Sabbath, Zep , AC/DC, stuff like that, I like an H-H Gibson scale type rather than the "Fender" 25.5 scale the Kelly has.