Totally agree about the round head being a hassle with the Better Beamer. It just doesnt sit right and slips too much. If you want to save a ton of money and still get that fast recycle time, you should look into the Godox V860II-N TTL Li-ion Flash for Nikon. Honestly, the older version is a tank and you can usually find them for a steal these days. It uses the li-ion battery pack which is basically essential in the cold compared to standard AAs. Since youre headed to Alaska, you could actually buy two of these for way less than a single SB-5000. Having a backup is huge when youre in the middle of nowhere and gear starts acting up in the snow. Just keep your spare batteries in an inside pocket close to your skin to keep them warm... it really helps with the recycle times when the temps drop. Good luck with the eagles!

Honestly, you dont need to drop six hundred bucks on the Nikon brand name to get great results. I have been using the Godox V1-N TTL Li-ion Round Head Flash for Nikon with my D850 for over a year now and I am super satisfied with how it handles. While the SB-5000 is the gold standard for some, for wildlife, the Godox Li-ion battery system is a total game changer compared to fumbling with AA batteries in the freezing cold. Heres why I think it fits your Alaska trip perfectly:

• The battery life is insane. In cold weather, standard AA batteries lose juice fast, but the lithium pack in the Godox V1-N TTL Li-ion Round Head Flash for Nikon holds up much better in the chill.
• Recycle times are basically instant at lower power. If you are tracking eagles and need that fill light for a fast burst, it keeps up without skipping a beat.
• High Speed Sync works flawlessly with the Nikon system. I have pushed mine to 1/8000s for birds in flight and the exposure is consistent every time.
• Better Beamer compatibility: It fits, tho you might need to snug the velcro strap a bit more because of the round head shape. If the round head makes you nervous for the Beamer, maybe look at the Godox V860III-N TTL Li-Ion Flash for Nikon. Its basically the same internals but with a traditional rectangular head that fits the flash extender perfectly. You could buy two of those and still be under your $600 budget... which is exactly what I did for my backup kit. Good luck in Alaska, it is gonna be epic.

Unfortunately I've had issues with that round head design when using the Better Beamer Flash Extender. It's just not as secure as standard rectangular heads. Since you're on a budget:

• Grab a used Nikon SB-910 AF Speedlight because the weather sealing is way better for snow.
• Try the Godox V860III-N TTL Li-Ion Flash for Nikon for faster recycle times. The Nikon build quality handles the cold way better than Godox tbh.

Been using this for years, no complaints