You are like me. I picked it up 1.5 months ago and rode dozens of time. 5'-7" 170 lbs. I got an S3. I am really between S2 and S3. Technically I could ride both. Unfortunately, I feel like S3 is a bit big for me while I felt S2 was a bit small for me. I wish there was S2.5. 😂 If you want to do more jumping, tight corners and switchbacks, and such that need more maneuverability, go for S2. If you need more stability for faster downhill and such, go for S3. I know it's hard...
