I initially didn't expect much from the GRS 8SW-4 but since I was running through all my 8" woofers, I had one of these and it fit the woofer cutout I dropped it in just to check and too my pleasant surprise it had a very smooth frequency response up past 2 kHz which made suitable for this design.

The woofer does have a rather high Qts and this results in a small bump in the bass response centered around 80-90Hz,  I ended up using a little less BSC to prevent that bump from becoming boomy which leaves a shallow dip in response between 150-300Hz.  The slightly lower energy in that range gives the speaker a subtle forward sound to the midrange and treble though not excessively so, with the lower bass bump providing a nice little bit of additional kick to most drums in music.  Bass response is ok, with an f3 of about 58Hz (4pi) it makes it fine to run without subs if using for background music but you probably want subs if they music you are listening too had any kind of deeper bass notes.  On that note since these are sealed they would respond well to some EQ like a shelf filter to extend the bass response if used at modest output levels.

 Distortion performance from the woofer is nothing special, it's a basic design after all.  At low output levels harmonics are mainly 3rd order and the more benign 2nd order harmonics take over at higher output levels with no erratic behavior up to the 105dB sweep level. Actually it performs reasonably well in the upper bass/ low midrange at the higher sweep levels compared to the Silver Flute or Dayton SD215 but being sealed low bass distortion is higher due to the increased cone excursion.    

The high frequency performance/sound quality is largely the same in all the designs so this section will likely be a cut/paste for each.  The LaVoce DF10.101LS with the Celestion H1SC-8050 is a very nice combo, the smooth easy to work with  frequency response  results a very clean clear uncolored high frequencies with remarkably low distortion and compression.  The high frequency driver has to work very little in this design so its composure is maintained well beyond the point where the 8" woofers are begging for mercy.  The only negatives are the slightly narrower coverage of the horn then I would have liked and the early drop in high frequency output past 16kHz.  For the cost I don't mind as they are not glaring issues that you notice immediately and the narrow dispersion could actually be a benefit depending on the desired use of the speakers if wanting a more focused dispersion pattern to keep excessive energy off the walls.