I agree about the buffs, they are great.
But honestly, there are some units that are just better. The actual point system is not enough to fill the gaps, imo.
Sinergy has become an important part of the game, but many units just benefits greatly from certain bonuses while other units just are worst even with the same buffs ( i am thinking about the various daemonic buffing that i'v seen with extra saves, bonus attacks etc.).
About summoning: no, we never had a game with full summoning army involved. I will ten rephrase: summoning without going "full summoning" is not worth it. i'd just have my units on the field from the beginning, thanks. Also, when the mages die, what happens? you lose the the rest of your army. the common mage is just a lucky (let's say average) cannon shot away from death and altough i don't like cannons, a free people army WILL have some of those. and guess who will they be shooting... Also, about balancing: don't you really think that sigmarines are a step above the rest? really? i also found mortal chaos to be quite underwhelming without any help from daemonic forces.
then of course, the armies looks more balanced than before...with fixed stats this is the minimum we can expect. but fixed stats generate, in my opinion, a serious problem: 5 imperial militiamen at 5+ will always be better than 1 sigmarine at 3+, if you get what i mean. Seriously, i had 30 arquebusiers hold their ground an entire game VS 15 buffed plaguebearers and 5 big nasty khorne warriors (can't remember the name of the unit). 4 turns of ridiculous rolling, shure, but that is not good balancing. With WHfantasy rules, any edition, those arquebusiers would have melted the second round of combat, as it is only just and legitimate.However that is a different problem.
IMO, you can mixmatch units as you please, but when you find THE right combo, then is a matter of spamming as it always has been. Moreso with the current points system, where points differentiation is not-so-well implemented.
And then again this is clearly represented by the summer campaign results. Order armies are just stronger. period. But then again, that's my grumpy and beardy take at the whole world talking.
(i also miss older rules set so i might be slighly critical...