Without going into a Kubota / JD debate, you'd be moving up a couple of HP, moving up from 2003 - 2012??, gaining a FEL. The price of the FEL is probably 1/2 of that, so effectively the cost of the deal is about $4K. Financially it sounds like a good deal to me. For me personally, I can't imagine a CUT without a FEL / Bucket and in addition I find countless uses for a set of pallet forks. From that viewpoint, I don't see how you could be disappointed if you trade. Only you can decide if the features / ergonomics etc of the JD are to your liking.
You could check Tractorhouse.com to check asking prices.