Last January, I put 1 oz oak chips in a couple of shots of Jamesons, and let it sit for a couple of days. Apparently, the flavour extraction is very fast from chips as mentioned above. I brewed up the original French recipe for Killian's that Papazian wrote in Microbrewed Adventures, as a BIG Irish beer for St Paddy's (6.5% ABV). It was amazing, although a bit aggressive. Now, what, six months later (I'm on the 2nd keg) it just keeps surprising me, it has softened and is quite delightful. More for sipping after dinner though, definitely not a sessional!
Cheers
In any event, I'm agreeing with the "heftier beer" comment.