OK, a 45% carbon 430 cm mast weighs significantly more than a 460 cm 100% carbon mast.
The thing that's making yoiur rig seem heavy is the mast!
At 90 Kg., yes I think the larger Helium 8.5 would be the wiser investment if you want to get planing
A 2nd board would be a good idea, but the larger fin will be something you would need to get the most from your Rio M.
You do not need to buy a new fin, just a good used Tuttle or Deep Tuttle in the 54-58 range.
A 7.7 m2 would be much better than your 6.7, but an 8.5 m2 is really what you need to get the most
from the Rio M at your weight.
Also, I suggested the Helium as it's supposed to be a very powerful light wind sail.
But this will be a large investment as you need a larger boom and a 490 mast.
The mast and boom do not need to be new, and can be considered long term investments as you can
carry them forward to other newer sails that require a mast and boom of this size.
How much wind are you sailing in most of the time, and are there times during the day you would like to
sail but the wind is not strong enough?
Hope this helps,