I have both on mine as well; I just recently installed the hand throttle, though, and have not wheeled with it yet, so this is all opinion base (thus, take it at face value). First off, I agree that it is better to have both, as it is not one vs the other kind of thing... I think they serve different purposes, and can complement one another.
With the innertia ring, if you hit an obstacle, the Jeep will not stall as easily as without it. I have found it very useful when hitting the banks of rivers, with all the small/mid size rocks, you can idle and the engine will not stall that easily (although if you hit a big enough one, it will stall).
As for the hand throttle, the reasons I installed it were:
- To rev up the engine for winching and airing up (my comrpessor is an electric one, but it is still good to get the amps up to run it for longer periods, such as when airing up or using air tools with the spare tank)
- Better throttle control on fire roads and river banks with lots of small/mid size rocks (when you are in low range, and you are bouncing all over the place, your foot tends to press and depress the gas pedal, and this causes the Jeep to jerk around; with a hand throttle, you can keep a steady speed regardless of the bumps)
- Hill starts (if you stall out in the middle of a hill, it's easier to start and keep going with a hand throttle)
I have also tried it for shifting on my seat while cruising down the highway (my cruise control is currently not working), but I rather fix the cruise control than use the hand throttle for this (I dont feel as comfortable with the hand throttle for this purpose). Hopefully, the cruise control will be fixed this weekend, and I will not depend on the hand throttle for the 16 hour drive back to Panama at the end of May...
I also got the RE kit, as it was cheaper than the prices at the bike stores. Here's a pic of the hand throttle:
And here's a pic of the engine bay (you can see the hand throttle and cruise control going to the TB):
By the way, this is the type of terrain where I THINK I will be using the hand throttle for:
Rocky roads (OK, THESE rocks are on the small size, but I did not have pics of anything bigger; you get the idea, though):
River banks