Have you used a 270 before?
The reason I ask is because I'm fairly new to stalking as well and I contemplated going with a 270. Everyone I could find who was an experienced deer stalker expressed the view that they would much prefer a 308 over the 270 due to noise and, mainly, recoil. That may not be a factor for you but it is worth considering. For what it is woth I went with the 308 in the end and am happy with my decision and am glad I didn't go the 270 route.
I shot my first deer with a 243 (hill red hind) and it didn't move more than a few steps so I'm in no way anti the 243 but one thing I might suggest is that with a 308 you can load it to perform as a 308 or you can load it to, by and large, replicate the performance of the 243. Now, 100 grain bullets designed for large game in 308 aren't common but they are out there and in hunting situations will give you 243 performance as near as makes no difference. Should you feel that you would like something heavier then it is easy to go to 150 or 165 grain heads for the larger deer and if you want to go after vermin there is the 110 grain V-MAX. With each 308 you get a free 243
I would also suggest that the 308 can give pretty much the performance of the 270 in any realistic hunting situation with both throwing a 130 grain head at about 3000fps.
If you fancy a 243 or 270 then by all means go for one, or even both. Having made the decision recently myself I'm glad I went with the 308 and have no urge or requirement for anything different.