Interesting article, but I always baulk at the phrase 'resented paying the royalty' in the context of patented devices -- like the Hammond Accutronics spring reverb.
The whole point of a patent is so that an engineer/company can protect it's intellectual property and generate profit from it for a reasonable period of time. It's a concept that lies at the very bedrock of Western commercialism.
So to 'feel bitterness or indignation' -- the dictionary definition if resentment -- at that, especially from another manufacturer who endeavours to protect its own unique designs, too -- seems rather inappropriate, to say the least.
Sure, I understand that Vox might not want to have to load their products with the extra $1 royalty... but having made that business decision their challenge is to come up with a viable independent alternative... not be resentful that someone else beat them to it with a better idea!
And they did come up with a (borderline patent-avoiding) alternative, which did work to a reasonable degree -- although in retrospect it might have been better to cough up the $1!