tent advice for newbie please!

Hi, I am looking for a tent that I can take tramping for my two kids and I to sleep in on an overnight tramp. this is something i want to do more and more as the kids get older. They are 6 and 4. I went on a hour tramp (2 hour with my daughter) last year and it was great. My son wants to join us this year. When I go tramping I will be going with a mate, and between us we will be taking 2 tents, all the food etc. The kids might take their pillow/clothes but that will be it. I have narrowed it down to two options: http://www.equipoutdoors.co.nz/contents/en-us/p2590_Kiwi_Camping_Nimbus_3.html http://www.equipoutdoors.co.nz/contents/en-us/p2588_Kiwi_Camping_Hooligan.html The nimbus 3 is going for $150, the hooligan for $175. The hooligan will be more spacious and has a better vestibule with groundsheet. If my wife decides to join us at some stage we can all sleep in the hooligan. The only issue is the hooligan is 2kg heaver than the nimbus 3 (7kg as opposed to 5kg). Now what I am wondering, is will that 2kg kill me on a 2hr tramp considering I have my two kids gear? Is the extra 2kg that much, it doesn't sound it, but i could be heaps after 2 hours of walking/stopping. i am relatively fit if that matters. if i go for the hooligan will i curse that 2kg? any advice greatly appreciated!