I would want to replace the arms myself if they are indeed stock ones. 4" of lift is too much to have the stock arms. I know it doesn't bother some, but I hate the look of having the wheels (mainly noticeable to me in the rear) pulled forward and from where it should be when lifting it that much and still running stock length arms.
Not long ago, I would have been on the bandwagon of not needing to spend the money on the Currie arms or any of the other double JJ set ups, but through more and more research my opinion has changed. Besides fixing the issue I mentioned and being adjustable so you can eliminate possible drive line vibrations they also ride better or so I have read. The price of $1000 seemed crazy to me originally, but then I got to thinking about it and that is only $250 as set (front uppers, front lowers, rear uppers, rear lowers) which doesn't sound bad at all to me for what you are getting and I plan on having them once funds allow it. Added to that is the benefit that if you go ahead and get them and later on decide you want to do more and say get rid of the t-case drop, add a SYE/CV driveshaft, you already have the arms you need.