I've literally spent hours and hours on the ar15.com. I won't get my rifle for about 3 weeks so I"m deciding on some of the upgrades.
3 weeks is nothing... thats a great turn around time. When i built my sabre in April, I think the wait time for most pre-builts, from places like RRA, was more like 3 months.
I orded the flattop without the carry handle.
Good. You can always buy a carry handle later, if you wanted. No need to buy it now if you dont need it.
I'm still trying to decide on either the 10" or 12" rail. Speaking purely appearance-wise and cool-factor-wise, I'm having a hard time deciding as either will give me the practical usage I want and need. I like the look of a 10 inch rail with a cool looking gas block with integrated front sight. At the same time however, I think the 12" rail just looks very clean and gives me that extra inch I need for my natural grip span since I have really really broad shoulders. I'm leaning to either Troy or Daniel Defense Rails. Both are fine choices and both have the look I'm after.
I wouldnt' purchase your rail (longer or shorter) based on how broad your shoulders are. I am also a fairly decent sized guy (6' 200 lbs), but what makes the biggest difference is how long your arms are. I have really long arms, and I still find the most comfortable forarm position to be well behind the end of my 10" rail.... somewhere around 6 or 7" (not sure exactly). What the longer rail will give you, is obviously more room to mount on the picitiny, but will also give you a longer sight radius if you take the route that I went, which is a removable sight.
Also don't forget, that the longer your rail, the heavier your weapon too. Every ounce adds up, including 2 inches on the rail. honestly, I don't think you will use that last 2" on the 12" rail, but only you would know for sure. I myself chose the 10" simply because it was kind of "in the middle" of all the sizes, and since I coudln't spend any time with the rifle before I built it... it seemed like the safe way to go, and it works perfect for me. YMMV.
Troy, Daniel, take your pick. Both are fantastic. I think the Troy's are easier to mount, unmount (i forget why though...), and are a bit more affordable. However, quality is not sacrificed. My Free Floating Troy rail system is built like a tank, very well finished, A+
I'm not gonna worry too much about optics at this point. I want to get the gun itself setup exactly the way I want it and that will take some time to figure out. The rifle comes with a decent adjustable stock, but I'm sure I'll swap it out for a Vltor or Command Arms stock. It's just that sorda stuff I want to work out.
But regarding optics... I got to personally handle several different setups at my local shop. I found the one I like the best that gave the most flexibilty was the Aimpoint 3x magnifyer co-witnessed into the Aimpoint comp m3 red dot with the magnifyer on a cantilever mount that rotates it off to the side. That setup will likely change, but it's what I like a the moment.
Optics is the one thing I am completely ignorant to. I went with front and rear BUIS, which will work fine for most things until I have the time and money to research some nice optics. RIght now I can't even afford ammo, let alone an aimpoint