I used this tactic pretty much and made only good experiences with it!
my army didnt have one knight, but griffonbannerunit, 2 stubborn units!
combined with detachments of 5 or 6 handgunners or 12 FC!
the idea on this army was, to make it impossible for the enemy to see a weak part, there was no point where he could easily go through. and when he arrived at my units, he lost pretty much, because of the ari and the handgunners, so he would break upon my lines...
the detachments were used to give his units a certain direction, when he charged so he need another turn to get his units in position...
the only problems that came up, where psychology and heavy magic, since i am always playing with only one caddy!
it is very difficult to play with more than 250 models, but very tactical and the imperial lines can be, if you do it right, more hard to break than dwarfen ones...
things that served me very well in this army:
EC with meteor, holy relic, van horstman
the famous pegasusrider
12 handgunners with comm. and 2x6 X-bows... that holds every flank
to the problem with zombies, coming up everywhere:
tell your oponnent that he has to place his units 1" away from your units---> that give you more than 2" between your units and you can also have the pegasusrider protecting the flanks or you just place the units on your flank a bid diagonal... its a bit hard to controll all those models, and on tourneys there will be a time problem, but if you practise a bit you will see that almost noone can harm you and your army