Deepthinker, the two guns mentioned by Strangelove have in facts different shape barrels. You're not supposed to know, cause they're a shiny new series forthcoming on the market.
Strangelove, happy to hear that: you left the winter in Alaska, you lucky man! Hope you're having loads of fun.
On your question I just can give a theorical answer. The Caymans arrived in shops just a few days before Christmas and the stocks were soon sold out. I went to my local shop just to see them last week, but there were not any more left on the shelf already. The power of advertisement! But none of my friends or clubmates were among the lucky purchasers, so I have no first nor second hand feedback about that speargun.
Tracking:
the Cayman HF has an oval/ellyptical barrel, hence it's supposed to be better in left/right swinging, but not so good in the up/down. At least, this is my experience with the Seatec Gabbiano, a very good gun whose barrel has quite the same shape of the Omer HF.
The Cayman carbon has a round barrell, which makes me think it's a better overall reef gun, but for BIG fish I'd pick the HF, which has more mass to absorb recoil from double band heavy punch. But it's just theory.
Now my question: How big is blue fish down there? My biggest one in Tuscany was about 8 kg. I once hit a bigger one, for sure over 10kg, but it broke away.
Enjoy your tropics