As I said before, the technical side of amateur radio is being lost, or replaced with appliance operators that operates, but doesn't really understand what happens when they press the microphone button or hears someone on their radios.
FM works on the principal of Capture Effect.
https://en.wikipedia.org/wiki/Capture_effect
It takes a much stronger signal to receive an FM signal than a SSB signal.
That is the reason why SSB is preferred over AM or FM, along with the fact that SSB takes up less bandwidth.
As far as claims of being able to set up Cross Band Repeat and walking away from the radio, and using it to cross band repeat your handheld, I think you need to read the Part 97.
It is not as simple as that.
If you read the rules - and this rule is covered in your Technician Class License Exam - you cannot just set up a radio and walk away.
You need to have a licensed control operator at the control point, or a second radio that can control the Yaesu 8900R that can turn the radio off if it has a problem - such as being stuck in transmit, harmful interference, having someone else operate on your transmit frequency - and causing problems, etc.
Each radio needs to transmit an ID every 10 minutes, not just you and your handheld radio.
The other way around it is to have a controller connected to the radio - much like a repeater, that is connected to a Private Line Telephone with an unpublished phone number, that can control the radio.
I think that the problem with new hams is that they learn the rules just long enough to get the license and then they chuck the rules out the window and they believe that they can just do what they please - just because the radio offers this option. That is what gets us into trouble.
Even when you have a 2nd radio on a frequency above 222 Mhz for control purposes, you need to contact the local repeater coordination council, because the frequency you chose, which might sound quiet, may in fact be a frequency designated for the control purposes of another repeater.
There is all kinds of things that you need to learn when you get involved with repeaters and cross band repeat.
And NO - a 50 watt mobile 6 meter transceiver will not always talk further than a 2 meter radio with the same sized - 1/2 wave mobile antenna.
All effective communications is Line Of Sight!
Anytime you place something between the transmit and receive antennas, it can and will block reception.
Depending upon the time of day, day of the year, or time of season, solar cycle, and location, propagation may or may not be enhanced.
I recently read an article that exposed the fact that the terrain in Pennsylvania is challenging, even for mountaintop locations, trying to get coverage over a large area of even just one county.
Digital modes such as D-Star just doesn't work well here!
For me, my money would have been better spent buying an Icom 7100....
All band, all mode, and 100 watts...