FlyGuy
I've fished with a Radian and a Helios 2. I've recently purchased and lawn cast the Zenith I got on clearance. All 3 were great. Also great are some of the older models that were mentioned (RPL, RPL+, Z-Axis, XP, Hydros to list a few). Is my Zenith light years ahead of the Z-Axis? Nope. Is the Z-Axis ridiculously superior to my 1994 Sage RPL+? Absolutely not. I hadn't used the RPL+ in a few years and dusted it off last spring and forgot how good of a rod it is / was. I have 9' rods and one 10' rod that is primarily used for nymphing. I have used it for dries and what it provides in additional distance was lost in accuracy.
I'll toss in my 2 cents....... If you are determined to buy a brand new rod, I won't try to talk you out of it. Cast every model you can get your hands on. I believe the blank profile of the Helios 2 and the Zenith are almost identical. The Loomis isn't far off from them either. At the same time, spending $800 on a new Helios or Radian would yeild 2 used rods which just might serve you a little better.
For the cost of one new top tier rod, you could get.....
Sage Z-Axis 9', 5wt AND a Sage RPL or RPL+ 9', 6wt.
Or
New St Croix legend Elite 9', 5wt AND an Orvis Hydros or Sage RPL, RPL+ or XP in 9', 6wt
Just a thought and good luck no matter which direction you decide to go.