So what you are saying is... a 500 (or 600+ for LSG) point unit, backed by a 100+ point mage works. I can see the buffs doing them wonders. In my last game I had a mage with them, and the Ward granted by successful High Magic spells really helped them out... many lives were saved. Next if only I could have gotten some damage in.
I am not sure why you find Seaguard much better... I get that stand and shoot can get some important pre-fight kills, but it is a very significant cost increase to get them. Perhaps you could elaborate?
Unfortunately, I currently only own 8 Silver helms, which doesn't quite do it... Need to invest in some more but I just haven't gotten around to it. (plus I need to build the ones I do have (they sucked so terribly before I never brought myself to do it)).