So, after a few (yet not nearly enough) games of 6th and some thinking I thought I'd throw out a couple of thoughts. Mainly on how 6th has changed what we should be bringing into our lists. This is not an absolute truth, just how I see 6th at the moment.
I talked about how transports had taken the role of gunboats in 5th. IMO, they don't cut it in 6th. There are a couple of reasons. First off, they're non-scoring and non-denial. Basically, this means that if your opponent's list can shrug off those shots that you're putting out, that vehicle is doing almost nothing. There are some things that vehicles are still good at (road blocks and losblock if you're not xenos) but they are certainly not what they used to be. Second, a cheaper tank (rhino) can do those same two things (road and losblock) for cheaper. Ofcourse, transports are also begging to give away first blood (which can be a crucial victory point). I don't see MSU thriving like it did in 5th, because the infantry won't survive without tanks and with tanks half of your 1+1 concept isn't committing 100% into the game.
That's not to say that some tanks wouldn't be useful. High AV vehicles or indirect weapons might even become more popular in 6th. Just remember not to spend too many points on them. Flyers are ofcourse very good, but there is the issue of how many to take. I personally am not as convinced with going all out. What happens when you hit a mirror match? Both of you flat out into ongoing reserves as neither wants to give the other the alphastrike. Eventually the guy who's going second will get it. On the other hand, if you take enough flyers to put a dent in your opponent's airplanes, maybe just enough to cause some damage and slow them down in a dogfight, you can have more points dedicated to ground forces and thus "win out" on holding your airforce in reserve. Your opponent will have to bring his stuff on first.
It's difficult to say which is really better in the current game system, shooting or CC. However, I'd say that more codices are equipped to build strong shooting lists compared to CC lists. Some armies can make pretty brutal assault armies (I really have faith in daemons) but most armies have clearer avenues for shooty lists. Certainly, shooting is still easier and demands less commitment, but antitank CC and new wound allocation can make CC lists very viable.
Finally, when thinking about your armylist, go through the entire codex, unit by unit. The new edition can have made surprising units viable again (I have great faith in Eldar Support Weapons). You also might not want to take mephiston into every BA list. A second HQ is almost a must, so that mephiston isn't your warlord and that really adds a pretty steep hidden cost. Don't be afraid to try new things. I am, and failing every now and then.