"NOT a scanner antenna" <<<--- Pishaw, as every antenna is a scanner antenna when all you're doing is receiving.
Now, taking that statement with a grain of salt you can improve things by having an antenna that's band or frequency tuned to resonate better at a given frequency, sure, but overall any antenna is a scanner antenna. As for the RH77CA it's my trusty companion, has been since I bought it back in 2005 and I wouldn't get rid of it for anything. It does extremely well for me - note I'm stating "me" there specifically - across the 110 to 940 MHz range just fine without issues.
Sure it's designed as an antenna meant to be fully capable of transmitting on the most popular Ham bands, 2M and 440, but since it's still just another piece of wire in the basic respects it'll work as a receive antenna just fine, especially on bands/frequencies that are working harmonics of the 144-148 and 420-450 MHz ranges - hence this antenna "works" for the MilAir band (first harmonic around 288-296 MHz, smack dab in the middle of the MilAir band) and the 800 MHz area (first harmonic of 840-900 MHz, basically right there where it should be), and a little more in the 900 MHz area as well (close enough to work).
If I attach my 1/4 wave 800 MHz ground plane I made to my RTL stick and tune in a specific control channel in the 800 MHz range (854.7125) for the largest system in my area and then turn the RF gain down to about 3.7 dB I'll get a peak on that signal at about -20 dB solid; if I remove the 1/4 wave ground plane and then put the RH77CA on without changing anything at all, I still get the -20 dB signal (yes, it's incredibly strong, easily hits 0 dB or more if I don't watch my RF gain settings). I also get the same readings with the RS 800 MHz antenna which is my other trusty companion and forever to be part of my antenna arsenal.
If I tune to some less strong signals I still get similar performance across all three antennas, oddly enough - this could have to do with the fact that I'm "at the bottom of the bowl" for the most part: Las Vegas sits inside a valley on the bottom of it because we're completely surrounded by mountains on all sides and the antennas for all the major communications are placed on sites at the top of the ridges for the best coverage. Because I live in downtown Las Vegas I'm literally smack dab in the geographical center of this entire metropolitan area 360 degrees around - I'm in the bullseye, literally.
As for the Wilson, I can't speak for it as I've never used one. And as far as the difference between the 801 and the 881, it could be the particular wrapping that creates the coils - one could be more tightly spaced than the other to alter the reception ability, I don't know.
I'd say if you are happy with the RH77CA, keep using it (which I'm sure you will do). If you want to check out the Watson(s), do it, if they're not what you expected or hoped for, return them - you're the only one that can truly judge how well a given antenna will work for you based on hands on testing which means you've got to get the antenna(s) to know. Remember: they're all basically pieces of wire or metal so all of them are "scanner" antennas in that respect - they can be different in form, size, shape, etc, but in the long run the basic principles are still the same, it's a resonator first and foremost so even a long piece of wire can pull in most anything at all, some better than others based on length and resonance.
You already know all this stuff anyway.
You know you've a scanner enthusiast when... someone asks you if you have a wire coat hanger they can use and you instantly say "Give up one of my potential antennas? NEVER!!!" 
