I have some Meprolights that I installed new about six or seven years ago now, and they seem to be about as bright as the new set I just put on a Glock I picked up. I dont see that they are any shorter lived than the Trijicons, and Meprolight warrants them for 12 years anyway.
Back when I first started using the Meprolights, they had bigger vials, a brighter dot, and the vials had a white ring around them, which the Trijicons did not. The last set of Trijicons I just replaced seemed to have larger vials and did have a white ring, although the rings were starting to crumble, so it seems Trijicon has upgraded somewhat.
While Trijicon may replace the vials at a discount, for the few extra bucks it costs for a new set of Mepros, and what I recover selling the old sets, I'd rather just go that route and not be down the gun time sending it or the slide back in to have it done. Then again, I do my own, so its a 5 minute job and I dont have the smith issue either.
I've always preferred the all green sights over the mixed colors. The green are the brightest, and have the plus of being the longest lived. I've never had any issues with confusing the dots, which some people seem to have trouble with. I dont really understand what they are doing to get them confused, but if its a problem, then use what works for you.