the 91xg is more like the european antennas by blake and triax
the cm4248 and 91xg are not a good comparison in my mind.
I installed the 91 xg at my home a few weeks ago and am pleased with the performance.
the 91xg should easily out perform the cm 4248 and prefer the design of the 91xg over the bow ties. the cm4228 is a powerful uhf antenna but is overweight and handles multipath poorly.
antennas direct publishes their gain figures in dbi ...to me thats cheating pulling a fast one but at the same time not lying.
dbi=dbd+2.14
16.whatever-2.14= 14.whatever in dbd which most reputable antenna companies publish
the computer simulation looks promising...but who knows what to really believe. dont see many lawsuits over antennas out there
http://www.hdtvprimer.com/ANTENNAS/comparing.html