A 623 in any model is a very productive machine in most materials except slabby gumbo, rocks and blow sand. I have a pair neither are G's, one is an E that has been repowered with G parts. The tier 3 C15 may not have quite the grunt of the 3406 but power is adequate and fuel consumption is less. The other is a late F with the same scraper as the G. The only negatives I can think of is the elevator chain adjustment was changed from very simply raising the small roller to a hydraulic grease and shim affair which is fine but much more complicated with seals to go bad etc. The other is Cat went to a smaller diameter roller on the rolling floor, we all know a big wheel turns easier than a small one. They are a complicated machine and need to be looked after, we grease every day. I can't comment on the G's joy stick control someone else probably can. Good luck, machine prices are way down here in the US and it's a good time to buy if you have the work. DP