He forgot to mention in the article itself that an IF out is required and not many radios have that today. I looked into this heavily and some radios can be modded to add one, however, it can void your warranty. Some radios have IF out options, but even so there can be delays so the views are not exactly near real time.
I've used virtually every possible approach to achieve panadaptor function with today's transceivers. The only time I've EVER seen any delay in the display was on the FTDX-5000 with SM-5000 speaker/scope. That is, beyond a doubt, the worst implementation of a band scope ever. If you want a first class panadaptor, you want an absolute minimum of hardware/software pieces/parts involved. The best pure hardware implementation I've seen is the Elecraft K3 with P3 panadaptor. It does everything you need (and in real time) and is well designed from a function standpoint. Every time you turn the rig on, it just plain works.
That might seem like a simplistic statement, but I've had configurations of hardware/software (including Softrock) where you had about a 50-50 chance of things working on any particular day. Too many software and operating system dependencies (drivers, etc.) and too many cables. If you want a first class panadaptor that can do everything that you can do with a Flex radio and PowerSDR (only better), you need to start with a transceiver with a down-converting design where the first IF is in the HF range, usually 8-10 MHz. For some of the Yaesu radios, you can buy a mixer card that mixes the high frequency first IF down to the HF range I mentioned.
The second thing you need is software to drive your panadaptor that supports your transceiver. That's key so that the frequency of the displayed signals is exactly correct IN ALL MODES. To do that, the software needs to know about the IF offset used for each mode. For my Orion II (with IF tap installed by me), I use an RFSpace SDR-IQ and SpectraVue software. SpectraVue supports the Orion II and many other rigs, and gets the IF offsets right. So, I can mouse on a signal in any mode on my PC screen and the Orion is tuned to exactly the right spot to receive the signal no matter what the mode. Why is this setup better than other approaches in my case (could have used LP-Pan, N4PY software, PowerSDR/IF, etc.)? For one thing, with SpectraVue I can shrink the window down to show almost nothing except the panadaptor display and I position that just above the Orion screen. It takes up little space and the rest of the display can be used for logging program windows (DXLab in this case). Another thing you need is the ability to access your transceiver CAT port from two or more programs at the same time (in this case, DXLab and SpectraVue). That allows you to mouse on a DX spot in DXLab and tune the transceiver and the panadaptor display to the same frequency instantly. And, mousing on a signal on the panadaptor is reflected back into the logging program.
In regard to voiding a warranty with an IF tap mod: Buy a used rig with no warranty. You'll save tons of money and won't be afraid to work on it. In most cases, the IF tap has already been figured out and well-documented by others.
Getting back to the comment on delays: Using the SDR-IQ/SpectraVue or LP-Pan/PowerSDR-IF (or one of the other display programs N8LP works with), there is NO perceptible delay. I can watch a CW signal on the trace and see that it perfectly follows the keying with no delay. Another thing you can do with the software I've mentioned that you can't do with a built-in scope even on the expensive transceivers is to vary the FFT parameters to affect the frequency resolution, smoothing, averaging. That's how you eliminate the "grass" on the scope so you can pick out signals better.
My advice is to avoid having several pieces of hardware and software to maintain just for panadaptor function. It will drive you nuts every time you upgrade your operating system and have to search for drivers for a soundcard, or replace your soundcard because there aren't any drivers for your new OS. Or, some key piece of software suddenly no longer works on your system, but works just fine on the author's system.
A panadaptor that is dependable and works well is a terrific addition to a station, and enhances operation regardless of the modes or bands you operate. One that works most of the time and/or is not well integrated with the transceiver is just more radio "bling".