It depends on how you plan to use it. I'm a big DNA200 fan but if you don't use TC or want to explore all the customization the DNA200 affords you, it might be better to get the RX. To me mods are tools I use to stay off the stinkys. Like any tool, it all depends on how you plan to use it as to which one would best suit your needs. I have the DNA200 version by the way.
Edit I think it's worth the extra money for me. I only use TC and like to add customization to my mods. I also got it when Ecig.com was blowing them out for $113 shipped (was a great deal). I'll add I have a few different DNA200 mods and it's not my personal favorite because it's a touch bulky and heavy for my tastes. It's comfortable in hand and gets great battery life but I prefer my DNA200's that use Lipos because they are smaller' lighter, and more pocket friendly. That's just me, we all have different wants and needs.
Cheers,
Steve