The 34" pitch in the F100s is a good 3-4" more than QF/VA give in Y on their 737s, and with only 5 abreast seating in the Fokker there's less middle seats too.
And 34" is only 3-4" less than you get in the expensive Business class cabins of the 737s.
Expect to see lots more F100s and F70s in our skies now that Alliance and Pixie have hoovered up most of the remaining F100 and F70 fleets of Austrian and KLM.