I can't speak from personal experience about Gull Barracudas, but have you seen the following videos of swimmers using them?
1. Freediving in the sea with white Gull Barracuda fins
[video=youtube;sC_4bDLjGaw]https://www.youtube.com/watch?v=sC_4bDLjGaw[/video]
2. Underwater swimming in the pool with orange Gull Barracuda fins
[video=youtube;Fr_nJjfK4P8]https://www.youtube.com/watch?v=Fr_nJjfK4P8[/video]
I own a pair of Gull Mews, which I use to snorkel in the North Sea, and I've always been delighted with the quality of diving products made by Gull Marine Sports in Japan. I do know that Gull Barracudas are the longest natural-rubber freediving fins in the world. They come in two sizes, Medium and Large, the latter having an overall length of 780 mm and a pocket accommodating a foot length of 270-280 mm. My foot size is nearer 290 mm and the fins come with a high price tag, which is why I haven't bought a pair of Gull Barracudas.
I am hoping too that your thread will attract further postings, possibly from freedivers living or working in the Far East, where the fins are more readily obtainable. It's good to see continuity of interest in, and production of, all-rubber fins, which have remained my personal choice in swimming fins since I began snorkelling back in the later 1950s. If you want to expand your search for opinions of Gull Barracudas, do remember that there are forums, both here on SB and elsewhere, dedicated to freediving and snorkelling.
Finally, here's a picture of a pair of Gull Barracudas, black this time:
David