I'm speaking from the perspective of being a very, very happy 4004 Cheyenne owner, a 1994 walnut/maple. It is truly one of the best-feeling, best-playing basses I've ever owned (or played, bar anyone's). And it's ONLY SEVEN AND A HALF POUNDS! It makes my Esh's, Fenders, Thunderbirds, et al feel like Olympic-trial weight bars hung from from straps. I'm assuming the later 4004s are similarly lighter than the 4003s, even with paint on them like the Jetglo 4004 you're considering.
Do not expect the exact same tone of your 4003, as pickups, electronics, and even mass make a difference (the body of a 4004 is about 3/4 as thick as a 4003). When I got mine, it sounded a bit toooo dark (as most Cheyenne owners used to 4001s or 4003s will attest), and even a bit muddy. However, after raising and evening out the pickups a bit, putting a fresh set of Rotosounds on it, and most importantly installing a 500k CTS tone pot PLUS a .022 cap (vintage Sprague, in my case) to replace the .047 that was choking the highs, it's now got some great "traditional" Ric growl and snap.
Personally, and to answer your original question, I would be allllllll overrrr the chance to grab the 4004. Look at it this way: you have a 2008 4003. That's a nice instrument, but it's nothing really noteworthy as far as Rics go.... it's sort of the everyday modern black Ric you'd find in the Used section at a guitar shop. On the other hand, when was the last time you saw a 4004 in person or hanging around a music store? Or being played out, live? And, even though the current used-market value seems to put the 4004 just under that of a similar 4003, I predict that the 4004s will gather a bit more value over time compared to run-of-the-mill (i.e., '07, '08, '09 etc) 4003s, if nothing but for the fact that fewer seem to be on the market, new or used. Just my opinion, so don't bet the farm. (I recently passed on a 2007 Jetglo 4003 with a Toaster and case for $1,200 because, well, it was just another black 2007, and I wanted something different.... so I picked up the Cheyenne)
But Hell, even the 2015 Ric pricing shows the Laredo 4004 to have an MSRP some $300 *MORE* than a 4003!:
4003 -- $2,159
***4004L Laredo -- $2,459***
4004 Cii Cheyenne II-- $2,729
So, go for it.