Don't worry about the mast until you ignore the tension on the uppers and or the periodic replacement of the other shrouds.
- run the uppers as tight as you can tolerate (It's tough for boat handling) until you are comforable enough to sail with the spinny and watch how the upper mast bends in a gust. It really should never invert. Some people say that you use the main sheet to keep the mast from breaking - but my pockets are not deep enough for that game! So I make sure the uppers will hold the mast vertical with no mainsheet tension.
- The spectra/dyneema degrades in the sun so keeping an eye on how much it is degrading is important. I'm probably too liberal in keeping my lines on the boat for extra seasons, but the other loaded lines often tell me what to look for in the shrouds. The spinnaker halyard will fray and eventually break where it goes through the masthead block and spends its whole life exposed to the sun. Likewise, or even more so, the tackline takes a lot of wear in the spinny up position (there is no swivel block there). So when one of those breaks or looks really scary, I fix it (yea - I'm cheap) and put shroud replacement on my off season to do list (so not totally cheap!). I also stagger the replacement of the uppers and lowers to spread cost out over time. For forestay and lowers, I just use material that is so beefy that it will last longer than either the boat or I will. Literally. 30 yrs from now my forestay and lowers will have 5x the working load they will need and the boat will be ending its useful life.
It's been a rough couple of days for me. I found out that a friend of mine died racing his Star boat last weekend. It sounds like he might have been hit by a microburst and jybed, and got knocked out of the boat. He was not wearing his PFD, and they retrieved his body from the bottom of the lake. He was one of the most respected sailors in the Colorado / Rocky Mountain region. But more importantly he was a truly excellent human being.
I know that the Swift keeps us all honest and respectful of the boat and the weather, but it still bears saying yet again - Always wear your PFD, and if temperatures are questionable, wear your wetsuit.
Be safe, practice your recovery drills and sail with confidence - Philip