1) The NB4 not having this 'feature' is not a "problem". As a matter of fact, most Tx do NOT have this 'feature'.
2) If you're forgetting to turn off a car and/or switch to another preset, that is NOT the fault of the Tx.

I'm not trying to put you down with what I said...but, if one is using RC vehicles, then that person should be responsible enough to turn off (or unplug) one vehicle, before switching to & turning on another vehicle controlled via the same Tx. Is doing so all that difficult? I mean...seriously...it takes all of a few seconds. At the track I used to go to (before moving to where there's no track), I NEVER heard, or heard of, anyone 'complaining' that their radio didn't have such a 'feature'. This is a 'feature' for "lazy" people.

I'm sorry Panther, but that is a very uninformed opinion, and you are disparaging a large group.

If you are racing, and signed up for 2 or more classes, it is very common to race, leave your car on so the cooling fan continues to run, and turn on a 2nd car to run another class. It happens all the time. If you never heard of it at the track, it is most likely because Sanwa is the dominant player, and most have Safety Link enabled.

It should be pointed out that Safety Link is not enabled by default. And must be set during the Binding process to specify the ID of the Receiver for that particular model.

99% of people dont bother to read the manual, to realize that they must put the Safety Link ID number to something other than the default "01" in order to have the radio specifically bind exclusively to different receivers, for different model memories. It is absolutely 100% possible to control two models at once with any Sanwa radio, provided you do not set it up properly.

That being said, i also hardwire my fans, so if i need to cool my car down after a heat, i can simply turn off the ESC, and the car will still be cooling away, just fine. I also have Safety Link properly configured, so that may be a bit moot...buuuuut...i would rather not take the risk or relying on technology to do the work for me, when i can physically correct it by turning off the ESC (and bus power to the receiver with it), or disconnecting the battery.

So I just got done checking my NB4. I turned on my 4 wheeler, and ran it as expected. Then, without turning it off, I switched on my 2wd buggy, switch the model setting in the radio to it, and was able to operate the 2wd, without the 4wd acting up. I did get a warning pop up on screen about having the receiver's fail safe set properly, but other than that, no issues.

I know that not all people need it, but for some, it's a good feature to have
I just hope that Noble can include this feature in the next update

I've tested the same thing, but both of them activated even if I change the model

Strange, I'm using their FGR4S receiver, and with both cars on, I can only operate the one that is currently selected in the model menu.

Probably a 1way vs. 2way mode thing. If you run in 2way, most likely it will be single model only.

Ah.. I see
I'm running on 1 way mode

Anyone have any issues with running SAVOX servos with the FlySky receivers, particularly brownouts?

No, I have been running savox and FlySky for over 2yrs without issue.

Is there a way to attach a motor fan to an open channel and turn it on/off via the radio? I tried assigning SW2 and SW3 to channel 4 and set it to 3 position hoping that would do something. It did not...

You would need a switch with enough amps like the type used for lights on a crawler or a small brushed esc if you wanted multi speed .

I just want to turn it on/off

You need an Aux Switch

https://www.amazon.com/Remote-Contro...645786900&th=1