Should i leave my current job for a "better" one?

I am currently a survey crew leader for a small survey/engineer company. I have had this postition for about 3 years now. I have been with this company for 7 years, or ever since i graduated from high school. I am happy at this company, one of the perks of a smaller company is comfortablility, and an easier going environment. Im well liked here, and to be honest i have got it made. Except for my pay.. they dont pay me enough for the work i do. There are 2 other crew leaders here that make almost double what i make. Granted the economy has limited our work load, and here lately ive just been glad to have a job. Anyways, a few years ago i submitted my resume to a website like monster.com, and last week i got a call. This new BIG company is very impressed with my resume, and wants me to start working immediately. They want to pay me substantially more money, and everything appears to be "to good to be true." I have had an interview, and next week im supposed to have a 2nd. They appear to really like me. The only downside so far is the title of my employment would be 6 month contract - to full time. My question is, should i risk what i have now, and leave? What if after 6 months of me working they give me the boot? Ive been where i am so long that i accrue 15 hrs a month PTO, i have full benefits, i just dont make enough here. Me and my boss now are close, and ive told him everything, he says the only way to make more money is to leave, and hes completely for it. I just dont know if i should. Anyone have any experience with this? Im 25 yrs old, single, no kids, but i have a girl whos just itchin to get hitched lol