I'd say yes, it's totally worth it.  I've had gaming rigs, so I've always had pretty good video cards.  Poser's rendering has ALWAYS bugged me.  It certainly has IDL flaws.  BagginsBill is a wizard, and can eek very good results out of it but I am only a padawan, not a Jedi master.  I pretty much gave up on scenes (enclosed spaces), Poser's implementation of lighting would drive me nuts trying to sort things out. I've used BB's environment sphere and light meter too.

I've found Octane to be far easier in terms of the lighting to the hobbyist.  Place lights as you would in the real world, and it behaves pretty like you'd expect it.  I never got that in Poser.  All these tricks of IBLs and 50 lights trying to illuminate a scene.  I've tried Luxrender as well, and even with 3.8 GHz i7 it was just too slow for me.  For reference, I have two EVGA GTX 970 cards.  I think the pic linked took 5 or 6 hours.

Having to edit textures in Octane is a pain in the ass and the drawback, but the results I believe are worth it.

Warning!  Link has nudity.  Not my best, but here's one I re-visited in Octane.  Similar lighting.  Link to Poser version in description.

http://gator762.deviantart.com/art/Charmane-Play-Redux-523296678

Hi there 5-6 hour render with Octane is not the fastest there as I would expect from two 970,did you tried to render only with one card ? I know there is flaw with new GTX which seems are slower in Octane,but faster in OpenCL...

In therm of lighting in Poser,depends on scene and depends on settings etc.but is easy to achieve good results there and I would recommend to use Gamma Correction and Scenefixer for correcting materials,with Gamma Correction you don't need to use 50 lights 

Hope this helps

Thanks,Jura

Thanks Jura, I checked the benchmark demo they have and I'm at where I should be for speed.  It's a pretty big image (2560x1440), and a lot of specular materials.  Lots of things in a scene impact rendering speed.  I also used PMC for the renderer which is slower than Pathtracing, but I find better at removing fireflies.
As for getting good results out of Poser, I disagree about the ease of good results.  Even with all the tools you can get splotchy areas and lighting artifacts...  Again there are masters here at it, but I'm not one of them.  You will spend more time in Octane editing materials, but I find that I'm spending less time lighting.  And that's not to say I don't edit materials in Poser - buying Poser native stuff, sometimes I'm still tweaking materials trying to get better results.

I find for the hobbyist/casual user, it's easier to achieve better results with Octane.

I'm a convert now after buying it.  :)