North whip csc 2017 size

[PusherII]

I am a 92 kg tt rider but i want to learn on strapless. Already tried some strapless, no problem to waterstart and cruise but Is the only thing i can do for now.
I decided to go for a csc, and in particular in my zone there are some north deals for csc whip 2016 and 2017.
In 2016 the whip pro csc came in 5.2 5.5 and 5.7 sizes. In 2017 and following they reduced to 4.11 5.2 and 5.5

I found a great deal on 5.2 2017, that Is supposed to be for 70-90 kg, meanwhile the 5.5 indicated for >85kg.
Technically i maybe should go for a 5.5, but what should be the trade off? if i decide to go for a 5.2, Ita gonna sink if i am too heavy or can be ok and very funny? Because i feel the bigger Is the less funny would Be... does It make sense?
I would use in choppy small waves condition, and price would be 450 euro with pad and fins, brand new. Shipped by a shop. Alternatevely i could go for a 5.5 2016 used pretty perfect condition for 380.
No way to demo any of them. Needless to say the Seller say the biggers size 5.5 would Be enormous