I am kind of saddened by this discussion. It is easy to fault someone, but it will result in bands that are empty and perhaps that is not what we want.
The duplex discussion has been done before on this forum.
Personally, I don't think that "monitoring one's signals" must mean listening to one's own signal when transmitting.
You can easily recognize the stations that listen-to because hearing your own voice with the sat delay makes you stutter:
you cannot .... speak well .... while you .... are hearing .... your own .... voice.
Many of these stations also respond 1 kHz off or more when they respond to a call.
For me, monitoring means just that, monitoring. Seeing if someone tries to break into your QSO. Seeing if LEILA is asking attention. Monitoring the signal levels.
And for that, watching one's signal via some SDR spectrum thing is fine.
A simple approach I've used often is to have a laptop that shows the Greenhilly WebSDR page. With proper font size and a but of scrolling the page can be used as a transponder scope. And when enabling the signal strength plot (on "slow") you can really monitor your own signals. This isn't bad: broadcast stations use remote receivers to monitor their signals.
When you cannot / do not want to use Greenhilly for monitoring, there are several approaches still. I have a Megasat Diavolo twin LNB and use one port to receive and the other just gets 12V and I use SDR console with a RTL-SDR dongle to monitor the signals.
Another approach is to tap the receive port signal and feed it to the SDR dongle. Unfortunately, with the DXpatrol that results in a few issues: 1. on the DXpatrol unit, the clock on the LNB is switched off when the unit is transmitting so the LNB does not function during transmits; 2. one needs to look at the frequencies for conflicts.
As to the latter problem: in my station (based on the praised PE1CMO kit) the LNB gives 739 MHz out and there is a separate PLL to convert 739 MHz to 432 MHz using a 307 MHz PLL. So it was easy to add a 739 MHz tap and that is what I have. However, in my case, the transmit signal (also on 432 MHz) was leaking on the receiver and was mixed with the same PLL signal to (also) result in 739 MHz. I spent weeks puzzling why I had this big signal on SDR console during transmit: was the 13cm overloading the SDR? In my case, the leakage of the 432 MHz transmit signal, over the TX/RX relay, over the mixer, gave a big signal on 739 MHz (credits to Rene CMO for the clue!).
On my setup, I mitigated this by disabling the oscillator of the 307 MHz signal during transmit.
Unfortunately, the DXpatrol unit has some challenges here. The LNB clock disappearing during transmit is not helping. The LNB outputting directly to 432 MHz is not helping either because it is very hard to keep this signal out of the receive chain. So, self-monitoring may be a challenge with this unit
Should DXpatrol consider an upgraded design that does not have these issues (perhaps with a "739 MHz out" connector, which my PE1CMO unit has now) then the unit would be even more attractive. But the current unit can be made to work - just watch Goonhilly when you operate and you're done.