I just changed over from the Meprolight M21 (tritium/fiber optics like the Trijicon Reflex, best of the breed, IMHO) to the new Meprolight RDS. I loved the M21's ruggedness & simplicity, and the triangle reticle was both fast and precise using the tip of the triangle for precision shots.
However, there is the heavy lens tint which made it more difficult to use irons (no complaint w/it otherwise) and while more difficult than w/any other similar optic I've used, reticle washout can be achieved under certain lighting conditions.
The new Mepro RDS has nearly all the features I find appealing in an optic: wide FOV through the optic, AA battery w/long life (15K constant-on hours), motion-sensing auto-on/off feature, 1.8moa dot, .5moa adjustments (vs the M21's 1moa adjustments), good QD mount, easy to access/use brightness control and a price tag of only $379 was enough to convince me to give it a try:
http://www.7-62precision.com/mepro-tru-dot-rds-red-dot-sight-with-1-8-moa-red-dot/
Don't get me wrong, I would gladly use an M21 again if that's all I had available and not feel disadvantaged, but the new RDS simply does more of what I want an optic to do (YMMV).
Tomac