The senate is designed to run 34 mph, your running at 30 so to get similar performance you need to up size (it's a given). At 30 your two steps down in speed so if you size down two steps its borderline and could lean to the 71. If you can try both 69/71 you should. I think what you will find is that one will be more physical work and the other will feel like your lighter on the water . I ski the 2017, 71 @ 34 and it works very well even when skiing short line. My wife skis at 28 mph on my 2015 71 senate and she is lighter then you and it turns well for her and she likes not being as completely worn out as she was on her 68 senate which ran deeper in the water at that speed. I took a while to get her to try it, she was sold on the first ride. Bottom line either will work ,try both if you can. But, if you plan to ski 34 go with 69. I personally prefer the 2017 model over the 2015.