I replaced the white dot sights with TruGlo fiber optic/tritium sights on my M&P pistols as none were optics ready. To retrofit and equip them with RDs would be prohibitively expensive. Also, depending on batteries for HD/PD applications is prone to single point failures. I do have RDs on my three rifles. I am upgrading my M&P-15 with a Cosmic Tactical ACOG clone and will include a micro RD for close up use. All three have iron backups.