If you're dissatisfied with the T-3, go ahead and swap it off. I like the Remington 700 platform, but if your hopes are merely to save a few ounces, you might be disappointed. The 700 Mountain SS is listed at (2.8 KG) 6.5 pounds, while the T-3 Light comes in half a pound lighter at 6 even. By the time you scope the Remington, add a sling, and put a few rounds in the magazine you're at 8 pounds.
A Weatherby Ultralite in .308 comes in well under 6 pounds, but is likely even more expensive for you than the Kimber, and not everyone is smitten with the Weatherby stock design or the MK-V's multiple locking lugs. The CZ 550 Predator might be worth a look, but it's even heavier than the Remington.
The downside of the Remington 700s is that they generally require a bit of tweaking to achieve their accuracy potential. Chances are that out of the box, the T-3 will outshoot it. The good news is that 700s can usually be found cheaply enough that a few dollars spent on bedding and a Timney won't break the bank. That said I've never seen a 700 that wouldn't hold 1.5 MOA out to 300 with good handloads, although I haven't shot any of the new models. A minute and a half is good accuracy for big game hunting, where field marksmanship tends to be the limiting factor not the rifle's intrinsic accuracy. That said its desirable if the first two rounds out of the barrel hit point of aim. If those first two rounds out of a cold bore don't print together, then IMHO, the rifle needs some work.
