I finally have some hard oranges-to-oranges comparison numbers between MSS Code Factory 1.8 and 1.9.
With the addition of the GEL compiler and runtimes and other performance tuning, 1.9 takes 1m25s to create MSSBam110 as of 2012.02.18.
The 1.8 release takes 3m25s to produce idential code for 1.9.
That's a 68% reduction in the execution time. Not bad. Not bad at all.