LP - V-MODA's first foray into headphones with a very bassy signature that many on Head-Fi consider muddy and not well-suited for most genres of music outside of EDM, hip-hop and the like. This is the only V-MODA headphone I have never listened to.
LP2 - An update to the LP that better presents the mid-range and treble. I was surprised when I first heard these as I was expecting bass cannons ala Sony XB500 or *cringe* Beats Solo (HD). Maybe I'm just used to the V-MODA house sound, but these were no where near as bassy as I thought they would be and I found them very pleasing and not too far off from the M-100 sound. If anything, the mids lacked the M-100 clarity and the sound stage was a little more compressed. I think that based on your musical preferences, and the $100 price difference, these will suit you just fine.
M-80/V-80 - The M-80 and the V-80 are the exact same headphone. The V-80 has HBO's True Blood branding and a tweaked color scheme, but drivers and build are the same. Considered the most neutral sounding of all V-MODA headphones, these have a flatter sound with a slightly emphasized bass with good mid-bass impact. The bass impact, to me, hits harder than the M-100 even. The mids are very lush and forward and vocal driven music shines on them. They are great all-arounders and although I own both the M-100 and V-80, I still find myself grabbing the V-80 every now and again.
M-100 - I spent nearly a year on the M-100 development thread watching and reading and interacting with Val and other Head-Fiers as we crowd-sourced what would make an ideal portable headphone. The idea for the folding hinge was born there as was my and a few other people's urging for the White Silver color scheme along with the Boom Pro Mic and the Coil Pro Cable. The sound signature was heavily discussed and tweaked for months and months and in the end I feel Val and V-MODA developed an amazing headphone with a versatile sound signature that performs great across all genres of music. However, some people were miffed that that sound deviated a bit from the flatter, more neutral M-80/V-80 sound. I find the M-100 sound more pleasing than the M-80 and it wasn't until I compared them extensively that I realized I'm not a neutral-head. I prefer a slightly V-shaped sound and the M-100 does this beautifully. The bass is strong and extends deep while the treble is sparkly without ever being fatiguing. The mids do get pushed back a bit, but not in a detrimental way. They are clearer than the M-80 mids, but are also harder to pick out because they aren't as in your face. If only the M-80 mids could find their way onto the M-100...
I still say go for the LP2 given your musical preferences. Get the M-100 if you have other needs such as portability, occasional forays into other genres of music, and a choice of different color schemes.