For what its worth, I measured between the pickup and the bridge on my Essence 6. It looks to have a bit over 7/16ths clearance. Checking the Roland site, the widths for the GK2B and GK3B are 9/16ths. Thus, as mgirouard3 stated, it ain't gonna fit.
Digging a bit more, I found a Yamaha B1D pickup that appears to be compatible with the Roland system and only measures 7/16ths wide. Keeping my limited budget in mind, I think it's worth the risk to give this a shot first.
Thanks again for the guidance and suggestions!