Hi Smurfy,
Must admit that I normally play against the Americans with my Germans at my Local Club; when I'm not taking the Russian Horde across the steppes to reclaim Mother Russia from the facists.
Big Jim at the club is planning to run an American Rifle Company but so far we have only played 500pt games.
A few times I've taken a US Force I've either been a Tank Company or an Armoured Rifle Company.
As I see it, your biggest downside is the lack of effective 'Anti-Tank' weapons, each Rifle Company only has 1 Bazooka (compared to an Armoured Rilfe which has 5) and that the Sherman Support Tanks are the basic M4A1 model with AT of 10 (as you can't take the 76mm Cannons) - can take on Panzer IV but is not really good versus Big Cats like Tigers and Panthers.
Remember reading somewhere that the Allies where expecting loses of 5 Shermans for every Tiger they managed to kill....
The Good news is that your basic selection of
HQ and 2 Combat Platoons is very cheap at 355pts. A good defensive base on your objectives - always dig-in - this will limit the damage from those MG HalfTracks as they will have to roll 6's on Fire Power to get you.
Then with the rest of your points, 105mm Artillery Batteries are a great option, get a good ToT (Time On Target) and that should keep Jerry's heads down, plus at AT4 & FP4+ this should scare any German Armour into hiding or spreading out.
Also Its worth having some Mortar Platoons - not for their killing power but for Smoke - good placement will cause the German Armour to have to move and therefore lose their
RoF 2 (or worse RoF3 for those Tiger Aces).
Air Support - as you can buy Priority flight of P-47 Thunderbolts - Battlefront models a bit expensive but if you look out for the Airfix Mini-kit set you can pick up a P-47 Thunderbolt for £2.99 - the size is 1:100 whereas the BF models are 1:144
The good news for me is that they are already painted (just glue together) and at £9 for a flight than £32 it's a bargin, especially when they don't always turn up.
Finally, remember the game is about Objectives (though 1 guy at the club always plays to break his opponent).
So as you will be spending most games defending - sit on those objectives and drop big templates on him from the board edge.