I don't buy that at all. Programming one more squelch code on a channel as opposed to another channel AND another squelch code is HALF the work. All you have to do is make the menu system easy to use. Simple!
3 mS delay? More like 30 mS! And it DOES delay opening up to what you want to here if the second (or third...) channel has the matching squelch code.
And you would see the same delay if there was some "multi-mode / multi-squelch" setting for a single conventional channel. The root problem is this: unless you want to start paying more for your scanners, it's likely the device doesn't really have the processing power to look for "digital with NAC" and "analog with CTCSS"
at the same time.
Instead, what you'd have is:
1. presume you have a channel programmed as "
P25 with NAC 123 OR analog with CTCSS 179.9"
2. scanner tunes to channel
3. RF squelch opens on an analog transmission with CTCSS 179.9
4. scanner sees your multi-mode settings
5. scanner first looks for "digital", with some timeout
6. transmission is analog, so the scanner times out looking for digital
7. scanner falls back to analog, and starts looking for CTCSS 179.9
8. scanner gets the CTCSS tone and unmutes audio
The example above uses "scanner looks for digital first / transmission is analog". The same problem occurs if "scanner looks for analog first / transmission is digital".
(The above isn't based on any knowledge of Uniden scanners, of course. It's meant as a general description of "the problem".)