Looking for some help with sights. I need sights for a flat top AR15 need both rear and front sights, BTW pic rail mount front and rear. Use for this gun will be mostly iron sights. Plan to add EO Tech after mastering the iron sights. My question is should I spend the extra money for flip sights, like Troy's or should just get fixed sights since I could simple remove if I needed to scope the rifle for some longer range shooting. Has anyone had issues with removal and replacement and sights no longer at zero?