Your brother's 08 is nowhere near the same bike as the Dyna! You should ride both to see what I mean.
I have a 2003 Fat Boy with 21,000+ miles that I bought new. I HAD a 2001 Fat Boy but got taken out on it hence the 03. The bike took such a
good head on hit that I bought another. I didn't consider the Harley early on (in the 70's) due to dependability issues. I moved to Colorado in 99 and wanted to start doing some serious rides throughout the western US and Canada. Got a wild hair up my old ass and bought the Harley. Both bikes have been VERY dependable. NO issues whatsoever irregardless of what some will say. The '01 would get up to 65mpg but wasn't much of a performer. The '03 is a non stock performer and gets 40 - 45mpg if I keep if under 80mph. Some of the advantages I enjoy (which you won't be able to) are no spokes, no carburators, fuel injection, no chain, counter balanced rubber mounted engine. As far as spare parts go there are a million take off parts available for a song and dance (look in my basement). After market parts are endless. Performance upgrades are endless. You can just about take these engines as far as your billfold allows. As far as maintenance goes, I did my initial recommended services which seemed kinda expensive but I wanted to preserve my warranty. Now I put it in the shop at 10,000 miles for a new rear tire and 21,000 for both. I change my oil. I switched to synthetic at 10K and noticed much improved shifting as far as finding neutral goes. Couple spark plugs every 10K or so. Gas and go is my motto. I have been totally impressed with my Harleys.
Now if it were me I'd keep that fine looking CBR for blitzing around and somehow manage to get the Dyna too. 2 totally different bikes you will appreciate but I'll bet that you would miss the CBR. I have never ridden a CBR for 2 reasons. 1 - I'd probably kill my fool self and 2 - my garage is too small and I'd probably bring one home if I rode it. I think my wife would get pissed if I asked her to park her Pilot outside