Here is the deal on long arms. It mostly depends on how much lift you are running in front. It looks like you have a 4.5" front spring with a 2" spacer. I am assuming you have a 6.5" total or something close to that. Also pictured is a drop bracket which is the minimum extra equipment needed for this much lift. Now, I am of the opinion that any time you get above 4.5" of lift you need long arms. There are several reasons for this. First, there is too much movement for those short arms to accommodate. Second, the ride will be improved with the longer control links. Third, as has been stated, it is easier to control your castor angle on the front axel which is a key thing to do so you don't end up with death wobble when your done. And last, you get better flexibility with the longer arms even though you already have drop brackets. You will find those brackets will catch on things.

So as yo mentioned, there is a cost trade off. The hardware costs money. So you will have to decide how much you want to put into the vehicle and what you want it to do and weigh that against cost.