Here's the quote of my personal message to a forum member who asked me for feedback about the XXV Gold. Since there are many guys interested, I'm sure he doesn't mind if we share these impressions in public.
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In my life I've owned 26 different types of spearguns, and shot with more than 50 types if I consider the ones I borrowed from friends.
I came to the conclusion that the XXV Gold is the best I've ever had for inshore-reef bass and mullet hunting. What makes it special is the size of the barrrel: just 25mm of diameter, instead of the 28mm of the other guns (Beuchat, Picasso, Comanche, Excalibur: they're all 28). The main advantage of such a thin gun is that unmatchable smooth tracking, quick aiming, instinctive shooting on small close targets suddenly appearing from the foamy and murky inshore waters.
The acessories are good as well: good trigger mech, a metal line release, very rigid and nice looking carbon fiber barrel, excellent rubber bands, the different configurations (open/closed muzzle, twin bands/circular bands).
My favourite option is open muzzle and screw in bands. With open muzzle tha shaft is kept in place by a loop of line, so it cant' move from the straight position during tracking. The screw in bands just because I'm more customary with them.
Of course, this gun has its downsides too. Which are briefly: recoil (but only on long length: no problem from 75 to 90), buoyancy/floatability, limited power, wishbone.
-Recoil: this issue is only related to longer guns. Buy a 90 if you want it or shorter, but DON'T buy a 100. This is a gun for agguato, for quick instinctive shots, not for long powerful shots. Its mass is too tiny to endure the recoil of a heavy punch. On short shots to a bass apperaing form murky you donpt have such issue, and that's the kind o task in which this gun is the best of them all. The "Gold" also has a full length rail, which helps accuracy despite the low mass.
-Buoyancy-floatability. Two problems: one of the downisdes of the very tiny barrell is that the gun doesn't float much. Don't get me wrong: it has a perfect negative buoyance shaft on and a perfect positive shaft off. But being so tiny, its mass is not enough push it up while hunting: it's your wrist who must do all the job. So that, surprisingly, I've had more wrist pain from this lightweight gun that from very heavy ones. A trcik I adopted to solve in part this problem: since I use it with twin screw-in bands, I use the muzzle hole made for the circular band to put in a cork (a cork cap from a bottle of wine). This way it's slightly better. But still if you hunt in waves, the lightweight gun will suffer more than a heavier gun.
-Power. The single band is very good for the bass task, but you CAN'T use double power. Choose whetether using the twin screw-in bands OR the circular. You can't use both because the tiny barrell, tho made in good quality carbon fiber, is not designed for such a heavy load. The trigger may as well feel more rocky and loose some of its stunning smoothness.
Wishbone- When you shoot it tends to shave the rail protruding above the barrel. So you have to fit your own knotted dyneema wishbone.
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To resume. I think your question is just: should I buy a XXV Gold 90cm or not? I bought it (even if mine was an 82cm) and I say: it's perfect for bass and mullet in short visibility. A 90cm is the one to pick, or even shorter 75cm or 82cm perform very well (while I wouldn't buy a XXV gold 100cm). The 90 of course has a longer range, the shorter ones are more compact and stealthy for lo viz and rocky bottoms. But if I was tyo buy another, I'd pick a 90 as it's a peculiarily light and handy speargun.