I love to hear reviews like this. Well done.
Your pics are also nice.
In general for GP, If it has a display caseback, then GP 03300. If not, could be a variety of ebauches or sometimes 03300 (case in point the 42/38 mm laureato Chronograph. Even when an ebauche is used, GP will typically work on it. Making changes and adding finishing and new levels of QA. The ETA 2892A is a good example of this and I quite like it. Reliable and solid.
For the spring bars, you can still use the quick release ones. You will have to bend them using the 2-spoons method if you do not have the nylon spring bar curving tool.
Glad to see you are enjoying your 4946 and posting often.
🤝