Mast for Severne Turbo 7.5

Anyone has any experience with GulfTech (GT) masts? Are they reliable?

I am trying to decide whether to go for the Severne Blue Line (75% carbon) for my 7.5 Turbo sail or the GT 75% mast... I wonder if the GT mast will help the sail perform as intended (flex, stiffness, etc...). I'd appreciate any input.

This will be my setup for the Futura 111 Wood Carbon.

The other piece of information I am curious about is the price differential in masts going from below 50% carbon to above 50% carbon. Given all other factors are the same (stiffness, curve, etc...), is it really worth spending almost like double for that 0.7 kg difference... Mind you that I'm the advanced recreational sailor looking for some fun speed runs, not racing or anything like that... Will I feel that difference in performance on the water?

Thanks much,
Hazim