In the end, these were the specs I went with:
Fermentables:
2.4kg of Maris Otter malt (72.7%)
300g of Crystal 60L (9.1%)
100g of Crystal 150L (3%)
150g of amber malt (4.5%)
100g of chocolate malt (3%)
250g of maple syrup (7.6%) - Added 1 minute before end of boil (slowly to spoon)
Hops:
10 grams of Northern Brewer hops (pellet – 10.7% AA) for 60 minutes
10 grams of Fuggle hops (pellet – 5.0% AA) for 10 minutes
And the final results:
Starting Gravity: 1.056
Final Gravity: 1.011
ABV: 5.9%
(80% apparent attenuation)
The color is definitely on the dark end of a brown ale, but when you look at it in the beer line, it's a much lighter brown. And when you put it up to the light or let light shine through it, there's a very nice reddish amber color, likely from the chocolate and amber malt. I attached photos of the beer line, the beer on a table, and up to the light to show the color.
The flavor is very smooth and pleasant. It ended up drier than I originally planned, mainly because the maple syrup was mostly fermented, but it does have a nice sweetness to it. Not at all cloying or strong. It's mainly from the crystal malts, I believe (though starting the mash at 68C/154.4F likely contributed, though I only used a towel to insulate the kettle and did not turn the heat back on, so the heat of the mash had dropped to 66C/150.8F after 30 minutes and was at 65.3C/149.5F after 60 minutes). Since I only had 7.6% of the fermentables as maple syrup, it only added a light hint of maple character. The maltiness is definitely far more dominant. The hops lightly support the whole. Overall, I think it's a very well-balanced and pleasant beer, but it's only been 3 and a half weeks since I brewed it. I decided to go pretty light on the carbonation to stick to style (though the ABV ended up also getting higher than I intended).
I'll need more time with it, but overall I'm very pleased.