Not sure which grips you're using, but I found using the stock foam grips gave me severe wrist pain quite quickly. I changed to Ergon GP1 grips (they have much better hand support) and now ride long distances without discomfort.
New York did some trials with UWB several years ago, which were claimed to have been successful. Since then, there has been very little news of permanent deployment or future developments either in New York or elsewhere.
Not sure whether this means that the various signalling suppliers are waiting for a customer to take on the technical risk of being the first to deploy UWB CBTC, or that there were costs or disadvantages that make it unattractive.
SelTrac has been around since the mid 80s, and was originally a German developed product (Standard Elektrik Lorenz) based on LZB technology.
My understanding of LZB is limited, but it appears to be a fixed block system with wayside detection of trains, albeit with shorter blocks than lineside signals would usually have. This is different to SelTrac which is moving block.
I had it done twice, both times without sedation by choice. I did have analgesics, and a cannula in my wrist in case I changed my mind mid-way.
It was quite tolerable, just a few moments of short lived cramping pains (similar to diarrhea pains) as the endoscope turned the corners of my insides. My recovery was about half an hour of sitting up and having tea and toast, while those that were sedated slept off the drugs.
I'd do the same again if ever I get another one, and recommend it to anyone who can't have or doesn't want sedation.