14.5" mid-length upper, fixed FSB, pinned 1.5 MB
What if before the MB was pinned I slid the FSB off and installed a 9" Troy Alpha rail? I’m not concerned with ME not liking it, but if I wanted to sell it in the future, would anybody else want it?
I think the ridiculous part is being concerned about modifying something you own because someone might not want to buy it
Let me rephrase…Are there any potential problems with the concept?
Lots of AR owners like those rails so what is the concern? I recently got two pinned 14.5" and for one have a Centurion cut-out rail that works with the FSB. For the second I am grinding down the FSB to fit a long free floater. Will that affect the value for future buyers? Yes - more for some, less for others. Different strokes.
Do it up how you like it unless it’s just an investment hedge going in the safe. Then leave it 100% stock.
No problem with the idea of your initial setup, nor is there an issue with your potential modification. As someone else stated, don’t modify/not modify your rifle based on resale…it is an AR, if it is a quality AR to start with, it will sell regardless of the configuration. I like a fixed front sight tower, but would not hesitate to buy your mod if I was in the market. Look at the Troy drop-in FF with the front sight pocket…you can keep the front sight tower and do NO mods to the rifle.
Concept is fine. If that’s the set up you feel you would like, shoulnt be any issues.
It would be ridiculous if the 14.5" barrel + 1.5" pinned muzzle device didn’t quite add up to the legal barrel length.
Sounds like a fine ideal,I have a couple ARs with that same basic configuration,Love them !! Like stated above,doesn’t matter what someone else likes,if its what YOU want,go for it,thats the beauty of the AR platform,same gun,a million different looks !!! 
You will be good to go with the 14.5 BBL & the 1.5 MB,it comes out to a tad over 16 inchs,as always double check to be sure,but it should be more than fine !! Don’t forget to post pic’s when your done !!!
The only issue I have is that you said you’re going to slide off the FSB before you pin the MB. Are you planning on installing some sort of gas block before you pin the MB? If not, you need to.
or he could run it like a bolt gun
If I was in the market, Id consider buying it (depending on make and muzzle device) shave the FSB and install a 13" vtac/troy
The greatest beauty in the AR platform is that you can have what you want, or can envision.
Being concerned about the disposal of it because you might become tired of it would seem to indicate that you have not yet thought this completely through.
My own opinion is that I would never assemble an upper that could not be disassembled without damaging parts; like cutting off a flash hider or muzzle break. Either do yourself the great favor of SBR’ing a lower, or if not possible, get a middy carbine if that’s what pushes your shoulder.
Not sure on the term concept being used to describe the ordeal. You just want to customize, but are reluctant to, as someone may not want it. Never understood people who worry about resale on so many things. These arent houses, and 1-2k is relitively cheap in the greater scheme of crap we all buy a year, so do as you please with it. With tacti-cool crap being popular, just throw an ncstar dot site, scope, some airsoft canted buis, a few flashlights, maybe a few lasers or 3 on it, and im sure you will have 0 issue selling it on tos if you do. Thus being said, I doubt what you want to do will even remotely effect sale value, or ease of sale. Gun stuff is extremely hot right now, and will probably be for quite some time, so either way you should be good.
I think he meant something along the lines of retaining the fsb like with a centurion install. I found this thread but couldn’t find pictures to see how it would look.