One issue I ran into using a FRFR guitar wedge in front beside the vocal wedge was when the stage volume got high. Poor FRFRs tended to not be pleasant sounding at higher volumes, the tweeters would overwhelm the woofers at high volumes and would turn the tone into a screechy trebly mess. But this tended to be somewhat related to the quality of the guitar wedge, high quality ones did not do this. High quality usually equals expensive.
I found two magic bullets for loud stage wedge use; load a 1x12 wedge cab with either a standard guitar speaker (a broken in V30 or G12M-25 worked very well), or a Kemper Kone (was gigging back then with a Kemper). BTW, here's an indication of the stage volume of this band; I used to use a Marshall JMD:1 50w combo as a stage monitor, pointed at my head beside the vocal wedge, and that did not have enough volume to do the job well. LOUD stages with that band...
Another thing; if you are looking for a 1x12 unpowered wedge to put a speaker in, it would be good to consider an old used Peavey 112M unpowered monitor. Pick the one with a piezo tweeter and the metal grille across the entire front, I bought one for $60 at the local GC. The drivers in this cab are hideous cheap crap, but the cab is very nice 5/8" plywood and well worth the price. But be warned; if you are considering a Celestion F12-X200 to put in one of these, you have to make the cutout larger. The stock cutout fits all other Celestions I tried with it just fine though.