Was the 7XC / R334 in SR mode, and/or was your 3GR / R603 in HRS mode?
From memory with HRS the reading should be 303Hz, if that's the case you must be right about the 200Hz limit on the SKYRC box.
C2 is an updated version with slightly lower latency than C1. I think there might be some hardware differences which is why there hasn't been much cross-compatibility unless the TX has a setting for both to begin with.
A little more here: https://www.rctech.net/forum/showpost.php?p=11504966&postcount=6

Thanks for replying, that was just what I was after. The 7XC was in SR mode but no SR servo. I thought FASST was 303Hz and it was definitely in HRS mode. It does seem the SKYRC box has a 200Hz limit according to the manual.

Thanks for the link about C1/C2 mode. I will check it out.

i apologize if this is the wrong thread, but i have this radio and am wondering if i can use the brake mixing to allow reverse in a brushless 5B while using mechanical braking. my thought process is to set the braking force in the esc down or to set the brake curve in the esc programming to not kick in until late in the trigger throw so the esc brake would only kick in on panic situations. thank you for any help

Futabausa.com have the version 4.0

Ordered my 7px Yesterday can't wait to get it!

Firmware can also be found through ripmax

Ripmax - Futaba Upgrade 7PX Transmitter

7PX Limited Edition possible glitches(?)
 

I've had my 7PX LE for a couple of months and raced for the first time April 13. Several people at our local track use Futaba 4PX and only one other person was running a 7PX. During the races, I had some irregularities that I've never experienced during practice runs. At times, it seemed as if someone else was driving. Throttle control seemed to be the worst with random out of control throttle/brake control. I was racing in several back-to-back races and noticed it was the worst if I switched to a different model without first turning off the transmitter. I'll call Futaba customer service in the next few days. In the meantime, does anyone know of any glitching issues to the Futaba 7PX LE?

Transponder near the receiver?

Can that actually cause problems? What about having the transponder close to, or on top of, the steering servo?

A transponder is a transmitter. Everyone says the low frequency of it does not interfear with 2.4ghz but still it creates a field that can have influence on the range.

I've seen vehicles with it attached atop the receiver case, on top of the service, inside the front bumper (of an Associated TC7.2), next to the ESC, etc. So, where is the best place to position the transponder?