Brad,
I went with ER9x - for me, the biggest benefits can be summaried in two words - flexibility & support.
With the 9x variants of FW, you are only limited by your imagination as to how you want to set up your Tx to suit your particular model and your flying style. I'll mention a few things that i've already used that were worth it for me (and these are quite literally only scratching the surface).
- ER9x allows you to use multiple timers simulatenously. So i can set a flight timer (total time in the air) as well as a count down timer based on what % of the throttle i'm using. That way i can work out what battery consumption i'll use at WOT and then the count down timer will count down proportionally. So if i know i can take 7 mins at WOT, the timer will let me go for 14 mins at 50% throttle. It's very useful! ... I know when my timer goes off, i'll have very close to 3.8v per cell left in my battery. I'll also know exactly how long i've spent in the air. No way you can do that with stock FW.
- ER9x also has an instant trim capability. So i can use my sticks to hold a particular setting and by hitting a switch (eg the trainer switch), that gets mapped into the sub-trims and the trims are set back to zero - all with the plane in the air. Very handy if you need to reset for different flying conditions (eg you want to fly faster than normal but still want level flight)
- ER9x allows you to set the Tx battery warning to whatever you want it to be. It also has a settable offset for calibration. Great for your confidence that you're not going to run out of juice.
- ER9x has ultimately flexibility with setting mixes to channels and switches. Want throttle on Ch1 - no problem! ... Want throttle on Ch1 but only when Throttle switch is off - no problem. Want to add in proportional down elevator (up to 5% normal elevator throw) once throttle moves above 60% - a little more complicated but still doable.
- Other things you can easily do with ER9x - Differential throttle (for dual motor planes), down elevator keys to flaps deployment, flaperons, spoilerons
Secondarily - support.
I'm yet to see anyone go into the forum with a request that hasn't been answered in a most emphatic way within minutes! The community seems to take it as a personal challenge to see how well and how quickly people are helped out. Lots of suggestions given when someone wants help with various mixes and ideas about how to achieve any even slightly unusual setup.
You won't get any of that with the stock FW.
Oh - and i didn't even mention EEPE (Well i have now
) .. PC or MAC based tool to allow you to do all your configurations on the PC rather than having to do it on the Tx. Configs can be backed up. There is also a simulator on the PC/MAC so you can check out what impact your changes will have before you try them out on the plane itself. Also will automatically download the latest FW upgrades which are always adding in new capabilities.
Lots more to talk about that i haven't even come close to using yet. I'll leave Malcurin to add anything he thinks is important too.
Cheers
Peter