The repeater is reachable in all most all locations, but not on handhelds, and if it is it’s vary unreliable. The desence is higher then I’d like when the repeater is in TX but it’s not really that bad at all compared to simplex. I’ve got a Sinclair q3220e and another can in the RX I can’t remember. But it’s not really about extending range just solidifying the coverage I have.
Any desense is too much. I've run plenty of 4 cavity duplexers in the scenario you describe (adding a bandpass cavity to the receive side) with absolutely no measured desense at 50 watts.
If you can hear desense, you're probably seeing at least 2dB of loss in the receive path. 2 dB doesn't sound like much, until you realize that 3dB better of receive sensitivity would double the coverage area of your system's portable talk in.
I guess it's human nature, but people will always pick the 4 watt portable over the 2 watt, yet how many of them will spend the time & money to improve the receive side of their repeater to gain 3dB? The net effect is the same. Getting 3dB of receive improvement will make your 4 watt portable seem like it's suddenly putting out 8 watts.