In my opinion, if you are planning on returning to Taiwan in the future, say one or two years down the road, then the advantages of maintaining the ARC certainly outweigh the disadvantages.
Every week I get complaints from people about the difficulty of applying for their home country CCRD, and all the other details required to (initially) apply for a JFRV.
However, if you don't object to going through all that hassle again, and being essentially a "non-person" (as you put it) for some period of time, you are welcome to ignore my advice, and use a tourist visa to come and go.
I would note that for a foreigner holding an ordinary ARC, there is no requirement that he/she be physically present in the ROC for any certain number of days per year.
You state that your bank accounts, bank CDs, credit cards, and private life insurance all use your ARC number, however I suspect that this is untrue. Commonly, such accounts use the foreigner's passport number.
If you maintain your ARC, you may continue to have National Health Insurance. In fact, you HAVE TO continue paying the premiums whether you use NHI or not. I get the impression that you want to be able to use NHI during your infrequent visits back to Taiwan in the coming year or two, so I won't discuss how you might apply to have the premiums "put on hold" and your coverage "suspended" during your planned overseas soujourn. (Obviously, all those kinds of details are readily available through your local National Health Insurance Office.)