well a stock f8 is worth around 170$? SOMEONE correct me if im wrong but thats what people will pay for them
add 40 to that and you have 210.. a used g4 will go for around 250 if your luck. the demand is just not there.. but to answer your question, yes that is a good deal if you would rather have a dp dump valve than a dp poppet.
the board in the g4 will be better, same with the trigger and arguable the reg. IT will be lighter weight and smoother. Efficiency is pretty good but not better than the f8
On my g3 iq it wont shoot. This happened to me the first time I used it but all I had to do then was raise the velocity. This time around whenever I messed with the velocity the air would leak out. HELP ME!