The difference of Master tier is one notch longer, "Hard" instead of "Medium" tees, but same "very fast" green speed.
You are a L56 TP with a 67.6 average. Me thinks, you need not hone your skills
- 30 and 33 scores are good enough!
Furthermore, your promotion (at 67.00 average) seems inevitable in a week or two.
You have decent equipment, only the irons may be a tad weak. Nevertheless, you might want to wait till L59 (88,000 XPs) to buy the G25s.
In the meantime, you might practice from the "hard" tees to see what will happen, or just dive in the fun of a new challenge!
I you want to "protect" your average (which will be reset and rise due to the harder conditions), you might want to enter a few unlimited tournaments (monthly and weekly) to allow for some buffer results under the familiar conditions, once you tiered up.