first question is ... what is your average wind speed of where you flying your kite ?
I understand that you looking into kite boarding on the water, instead of inland, correct ?
Well, this is my inland power kiting experience and what I know ... I weight just a tad more than you, 46.5 years old here and profound deaf (hard of hearing) ... Just started flying quad lines in March 2015
I believe that 4 lines 2 handles is much safer than doing 4 lines into 3 lines control/turbo bar, because if you panic and not knowing how to control it ... then you will more likely to pull the bar down harder to hold on tightly which will pull you harder or get lifted ... but it may never happens on 2m, but 5m for first timer ? You can decide and put safety first.
My Uncle's close friend bought 7.2m with control/turbo bar for the first time ... just starting off ... kite is going crazy and he tried to hold on by pulling the bar and hurt his back badly.
oZone 3m, 4 lines, 2 handles is what I started off and turned out too easy after in couple months and I can control that kite up to 24 mph wind which I did tested it myself to see if I can control my kite ... it was very rough, really rough (laughing)
I fly several quad lines kite inland and ride a couple of homemade buggy (wooden style & bike style)
For the last 6 month or so ... I got Rhombus 7.2m, 4 lines, 2 handles and it's amazing at 6 mph light wind while standing/pulling, but at 12 mph is very easy to jump and riding a buggy at 12 - 17 mph is like flying 3m power kite because the buggy is in motion.
Flying 7.2m on 114 feet lines will have much more pulling (kinda like g-force) than on 75 feet lines ...
I helped my other Uncle to get his first power kite, Flexifoil 3.5m (quad lines, 2 handles) is very awesome at 10 mph, but it will pull board/buggy better at 12 mph or more.
what RobB, kevmort & Mikelp3586 said is very good to start off with ... I believe you can start of at 3m, maybe not 5m in a high wind like 12 mph for that size, it's very strong if you are not riding on board or buggy ... but you can always ask someone who has one and see if you can handling it good before you buy the kite the one you looking for.
the best lesson is learn how to control the power kite which is your BRAKES ... learn how to use BRAKES a lot like a good habit and don't let the kite control you ... then you will know what to do next when the kite have gone crazy
at last, safety first ... then may the fun begins ... wish you the best.