Slow is hella good, but not as all-around powerful as stunbolt and manabolt, from my experience. A force-1 spell will pop if there's more than one PC or NPC inside it trying to move. If you center it on someone, they're proof against bullets... but they can't shoot out (Without a laser, and likely at a hefty penalty due to the aiming movements being, well, slowed!), and if they leave the area of the slow spell, they're vulnerable again. Standing still in combat = probably a bad idea. Especially in a setting where backup is a call and moments away. Very useful for a quick exit of a building, though. Overall, most of the functions of the slow spell can be covered by the use of Physical Barrier and Levitate.
Oh, with a good fixer/talismonger, it takes only a few days to snag the formula going by strict availability rules; GM may modify those as appropriate.
The biggest power creep from WAR!, IMO, is Softweave Armor. A BOD 3, STR 3 mage suddenly can stroll about in FFBA and a fancy lined coat, resulting in a sweet 12 ballistic, 6? impact armor. Had a GM going WTF over my character's defensive pools because of that. And at +10% cost, +2 availability, that is a cheap defensive boost.
No experience yet with battle rifles, though that's because the cost of the _ammunition_ is prohibitive at chargen. I suspect that once a character can make much use of such weapons, it will be like lasers and similar: when they can afford to use it, they will also have the karma, skills, gear, adept powers, etc. to be _very_ good at using it.