The only reason I would invest in LTC is in a pump and dump scheme. The only reason the price has risen thus far (AFAIK) is the speculation that when LTC hits MTGOX its value will skyrocket similar to the BTC bubble last month. The question arises that a rise in value either requires later investors with their speculation driving the price up or that there is a use for LTC for which BTC cannot accomplish (AFAIK LTC only offers fast transaction confirmation). Without a facilitating something that BTC cannot, i don't think there's anything that ensures the growth of value for LTC, other then greater speculation by later investors.

My 2 Shatoshi's
Shas