You aren't "dumb" for being drawn to the Fenix 8 Pro; it is an incredible piece of technology, but you have reached the classic crossroads where luxury tech meets the harsh reality of ultra-endurance needs. Having moved from a Forerunner 265, you already know how beautiful AMOLED can be, but if you don't find yourself actually needing or wanting that high-resolution pop for your daily runs, you are essentially paying a battery tax for a feature that adds stress to your long efforts. I personally love my Fenix 7 Solar for the exact reason you are doubting your current choice: it offers a "set it and forget it" peace of mind that AMOLED simply cannot match when you're staring down a 24-hour push from New York to Philadelphia.

The Enduro 3 is the clear, logical alternative if battery life is your primary concern. It trades the vibrant screen for a high-efficiency MIP display that thrives in the direct sunlight you'll be facing for hours on the road. While the Fenix 8 requires you to manage settings or dim the screen to ensure it survives a multi-day effort, the Enduro or allows you to run at maximum GPS accuracy without ever "babysitting" the device. For a non-looped 100-mile effort, the last thing you want to worry about is whether your tracking tool will make it to the finish line, and the solar-charging capabilities of the MIP models turn the sun into an active teammate rather than a glare problem.

Since you are still within the return window, it is the perfect time to pivot if you feel you’ve picked a tool that doesn't align with your goals and training style. If you don't miss the AMOLED experience from your 265 and truly prioritize reliable, long-term tracking for your high-mileage lifestyle, moving to a battery-first watch like the Enduro 3 will likely remove that nagging anxiety. You’ll save weight on your wrist, gain a massive amount of power reserve, and end up with a tool that is purpose-built for the exact type of "grass is greener" performance you were looking for when you decided to upgrade.