Well, I'm a tad embarassed.
Turns out most of my "shrinkage" issue was due to one badly created gallery wrap mirror that was off by 1/2 an inch. I took careful measurements on my last two canvas jobs and discovered the following:
1) After printing, before spraying, both prints were spot on for their dimensions. The 44" print was exactly 44" long. The 24" print was exactly 24". This is on LexJet Sunset Select Matte with their custom media type for the 8300.
2) After spraying both prints shrank by 1/8". That's right, only 1/8".
Guess I'm just lucky?
Neil