If you increase the table length, then tyranids and orks should come down a bit in price to make the horde army more viable as a rushing in.
Tau, increase in BS would probably make a bit of sense as they are a shooting army first and foremost.
I have also been thinking about this a little bit, but i think they need to go back to the days of having a separate strength for attacking vehicles. This would go part way to making gauss flayers less of an odd rule amongst other fixes. Glancing hit on a 6, i feel is ok for lighter vehicles, but i don\'t buy it against heavy tanks. Multi lasers/scatter lasers are also another odd one. High strength, wounds infantry easily and can damage lighter vehicles, but cant penetrate infantry armour? If it is good enough to go through the side of an APC, then it should be good enough to go through carapace (at least).
By having a separate strangth, it means that you could make it more in line with current weapons. For example, missile launchers should be great against vehicles (high vehicle strength), but lowsy against infantry (highlighting the difficulty of hitting someone with a weapon designed to destroy tanks). Lascannons would be good against both sorts of targets (it is a precision weapon) but is hampered by it\'s slow rate of fire. Plasma cannons should go back to 2 modes of fire, with the focussed beam being good against vehicles and slightly worse against infantry and the wider blast marker great against infantry but lousy against vehicles.
Small arms could be better, with sniper rifles having an appropriate strength of 7 against infantry instead of \"wounds on a 4+\" This makes it excellent against lower toughness imperial guard, eldar, tau, but will not take out a space marine commander or ork warboss in one shot. Hive tyrants, Carnifexs and Wraithlords will also be possibly better off, not sure. Bolters can get a higher strength against troops but lower against vehicles, las guns could get a bump against vehicles to represent it is a precision weapon. shuriken catapaults. excellent against troops, no chance against tanks.
But these are just some thoughts.