STEINER 440

So...if I am looking to trade my 4200 3lc gas Ventrac...do I go 440 or 4500??

I'd seriously consider keeping what you have... You already have the best engine,IMO everything new is a downgrade exc the 32.5 kubota. I'd stay away from the diesels in either machine unless your running light use only, you'll lack power in hard use, and heavy cutting conditions.