The M-14 barrel is too thin in the later section of the barrel, and with the gas cyclinder tension compounded by the FS weight, the barrel need tension to shoot their best. Trust me, too may people have tried to Float the barrels, only to be back at square one which is tension is needed on the barrels to make them group. The M1 Garand has the same problem (if you want call it that), and this is why the middle band clip also pulls down on the barrel.
As far as glass bedding, it doesn't matter if you steel inbedded glass or Dupoint, over time the bedding is going to break down, which leads to flyers/shifts in POI in the groups.
As for a scope on a m-14/M1A, never going to happen on any of the ones I own. If I want a 308 combat rifle, there is more than enough HK's in the safe, so why screw up one of my match rifles playing wantabe dress up. And really, if you need to scope a rig, then the M-40 is the platform of choice for long range or if you do need to go semi/full, the SR-25 fits the bill nicely.
No flame intended, just my take on the whole SAGE concept.