It really depends on how you record. If you're generally happy with your tone and have no desire to change anything after you've tracked, there's less of a need for Native. Yes, Helix Rack lets you re-amp after tracking both wet and dry versions simultaneously, but that's a massive pain IMO, as you're sitting there for the duration of the song x as many tracks as you need to change. Or you could slap Native on the dry track and tweak it at any time. Of course, there's something to be said for committing early so you don't spend years mixing a record only to have it come out terrible sounding anyway <ahem, Eric>, but I'd still much rather have the flexibility of changing things later.
Also, Helix Native is great on all sorts of non-guitar/bass tracks. I use it on vocals, keys, drums, busses, you name it. Lately I've been grabbing Retro Reel before any of the half dozen saturation plugins I have.
The main advantages are live performance, jamming, and (effectively) zero latency while tracking. One button press on my monitor controller routes Helix Rack directly to my studio monitors (digitally, so only one D/A), so there's never any need to boot the computer, launch Logic, and instantiate a plugin if I just want to play.