I was hoping you would have had some feedback by now. I've got a set of Kappas I plan on installing this winter, and have the same concerns.
Kappas went in. Speaker mounting holes align with the factory speaker holes (no surprise there). No issues with the magnet or speaker frame fitting into the factory speaker enclosures, so getting it all tucked in = no problems at all.
I knew that the Kappas had screws instead of spade terminals for speaker wire attachment so no surprise there (other than wondering about the engineering decision to go that route).
You will have to play around with the tweeter orientation to prevent interference with the stock grill. Luckily the tweeter domes spin around almost a full 360 degrees allowing for a lot of latitude in the orientation to clear the stock grill.
My factory grills snapped back into place without any problems once I had the tweeter domes properly oriented.
My main surprise was that I wasn't completely blown away in SQ difference between the Kappas and the JBL GTO368 speakers that I was swapped out. The Kappas sound and appear to kick harder than the JBLs in mid-bass and have a bit more lower end in them, but part of that may be because I stuffed my enclosures with polyfil since I was in there any way. The Kappa high frequencies sound like they have more detail, but there does sound like some dead space in the mids where the JBLs benefited from being a triax instead of coax design.
Strangely enough, optimal AMP gain and frequency adjustment on the Cerwin-Vega B2 were almost exactly the same between both sets of speakers. And I spent a lot of time on those with the installation of the Kappas. Setting baseline AMP gain using the DMM method, then tweaking from there using test tones and finally music. Same thing for the frequency adjustment.
Once again I opted to use the HP crossover and tweaked the frequency using test tones of 60Hz, 80Hz and 100Hz - 0dB. My full power range is kicking in at around 100Hz but still passing through some audio between 60-80Hz.
I'm hoping that over time the Kappas will break in and start to sound better, but I'm not sure based on initial impressions that they are $70 better speakers than the JBLs they replaced. I would have probably kept the JBLs and sold the Kappas, but some aggressive use of test tones and gain in the 400Hz range cooked the voice coils