I gave up on the TRS discount years ago when
ebay went to a tracking requirement since the majority of my sales are (comparatively) low dollar light-weight shipments. Letters with nonmachineable surcharges, not parcels, and thus ineligible for tracking.
Also, stamp collectors want stamps on their letters. Some get downright irate if you use PayPal/eBay shipping to print labels instead of affixing stamps.
No, the TRS and its ever-increasing hoops to jump through just aren't worth it. I have 3-day handling and I have yet to get a complaint about it. Occasionally around the holidays I will get a request to ship it the next day or by date X, as presumably it is a gift, but that's about it.