I tend to agree. I love QRP, but it certainly has its limitations. One thing many of the more popular youtubers don't quite demonstrate is that lower power is fine if you're the "DX" station. Meaning, if you're the POTA/SOTA activator, it's not a huge deal. Anyone responding to you can hear you, and people are actively trying to contact you. But if you're the hunter/chaser and there's a pileup, the people with the 59 signals are getting called far more often. This isn't to say that 100w = 59 signal, but having more power certainly gives you a better chance. Then again, 20w vs 100w will cost you about one S-unit, which really isn't a huge deal.
I definitely see the attraction to the G90. It's a very popular radio for a reason. I have the X5105 and when they say the Xiegu radios can tune anything, they can tune anything. Unless money is truly a factor, I suggest the 891 or similar as a first radio. It can easily become your shack radio later when you get something like the G90 for easier portable ops.
In the end, the best radio is the one you have.
As for coax, I would not use RG-8X for VHF/UHF. You're going to lose about 40% of your signal to the coax in a 50' run. RG-8 is a better option, or LMR-400. RG-8 is probably going to be easier to work with than LMR-400, and is cheaper, but is a little lossier.
Cable manufacturers will tell you the loss at a given frequency, usually in dB per 100'. Every 3dB of loss cuts your effective power by 1/2. You can drive yourself crazy trying to select coax. Certainly don't skimp, but coax is less lossy at lower (HF) frequencies, so you can always upgrade later and repurpose for that.
