If I was you I would ask David Ezzy: [email protected]
I would suggest the Cheetah 5.5m2 is best for you given your current board but see what David says and let us know.

If you think your next board will be used for tricks and manoeuvres then get the Zeta. For waves the Zeta will be better as the foot wont catch in the wave, same for water starting its easier to get a Zeta out of the water if you need to be quick before the next wave breaks on your head. But if you only get waves rarely then not a big issue. I have sailed on waves with a 7m Cheetah before.
If you are going to sail back and forth and gybing, with a few jumps, get the Cheetah as it will be faster.
I made a similar decision for the 6m sail size and went for the Cheetah and dont regret it. That was the older 7 batten sail, now they have 6 battens and are lighter.
I looked up the specs for the Zeta and the 5.5m sets best on a mast combination of 400 bottom and 430 top with a longer extension, where the Cheetah sets on 430. The Zeta would still be ok on a 430, will have a good low end power, but will have a slightly heavier feel and wont twist off so well in gusts.

I would stay with the Cheetah to keep the wind range spacing uniform. Plus you're used to the way the Cheetah handles so that's a bonus too.
And lastly the Zeta 5.5 calls for a 400/430 top/bottom mast combination and the Cheetah is a straight up 430. You can use a 430 on the Zeta but if it is anything like my Tiger it will feel much better with the 400/430 mast combo.

If you keep the Hawk 110 and get a smaller freewave board of around 85-95 litres to make it easier to perfect you gybes and jumps then this would make a great two board quiver to go with 6.5, 5.5 and later a 4.5-4.7 sail. For this setup I think the 5.5 Zeta would suit an 85-95 litre freewave board better then the 5.5 Cheetah would, particularly in bump n' jump conditions and the 5.5 Zeta would still work fine on the Hawk.

If you decide to change the Hawk 110 for a similar size freewave board then I think the 5.5 Zeta would still be the better choice for the same reasons.

As windfred said you would only need to buy a Hookipa 400 base to use with the Hookipa 430 top in the 5.5 Zeta.

fannan said..

GazMan said..
If you keep the Hawk 110 and get a smaller freewave board of around 85-95 litres to make it easier to perfect you gybes and jumps then this would make a great two board quiver to go with 6.5, 5.5 and later a 4.5-4.7 sail. For this setup I think the 5.5 Zeta would suit an 85-95 litre freewave board better then the 5.5 Cheetah would, particularly in bump n' jump conditions and the 5.5 Zeta would still work fine on the Hawk.

If you decide to change the Hawk 110 for a similar size freewave board then I think the 5.5 Zeta would still be the better choice for the same reasons.

As windfred said you would only need to buy a Hookipa 400 base to use with the Hookipa 430 top in the 5.5 Zeta.

Yes this is my thought also, that later ill buy a smaller sail (4.7 around).
David told me that i still can use the zeta 5.5 with my 430 mast (when ill get the smaller sail i can get also the 400 mast).
About the board now, thinking to keep the hawk for the low-middle wind conditions and buy a 90l freewave board, for the middle-high wind conditions. Unless ill find an 100 l freewave board in really good price, in that case ill give the hawk.

The other thing about zeta is that seems to be without any changes the last 2-3 years so i do not know if makes sense to go for the new model.

If there are conditions like in the video often enough, that sounds the best plan, 90l freewave, 5.5m Zeta and 4.7m later on. You will be ok for a wide range of conditions with that.