I'm considering taking a loan for 6,6k and building 3x ltc mining rigs which would total 9,000mhs, at current diff it looks like piece of cake, but need to know more about difficulty increase before i move forward.
I can't dissuade you from taking a loan out to get into mining enough. LTC is seeing the total network hash from GPU miners increase very quickly and there's also zero guarantee that the price of LTC will stay anywhere near where it is (It only recently went above $1 on the rumor of it being traded on MtGox)
As others have said, if you want to get into mining you are safest in not viewing it in a "get rich quick" or 1-3 month ROI type of deal. 9-12 months is a much more conservative schedule, and if things get tighter it may be longer than that. Keep in mind, also, that your electricity costs will be very real and noticeably different with 9k MHs running 24 hours a day. If you're not converting your LTC to fiat to pay that off, you'll be incurring costs along the way in addition to the loan interest.
That said, value could continue to grow for BTC, BTC/LTC, or LTC independently. It could also go to nothing.
Full Disclosure: I have GPU miners working right now and would make relatively less if you start mining! I only paid disposable or investment money, though, that I could afford to lose without a sweat. A loan is a much more risky decision.