I apologize in advance for any terminology mistakes...

Do any of the holographic or dot sights (Eotech, Aimpoint, etc.) have a changable reticle?  I.e. can you change from a dot to a triangle and back again?  

The only ones that I know of are the OKO, and the Hakko "electro-dot" sights. I've owned one of the Hakko sights, and was pleased with it; it was very well-made. I've read that the OKO is also a good sight.

Just to get in a plug for a couple of REAL good guys to deal with, the OKO is available from Cavalry Arms (GARRYOWEN), and the Hakko is available from Sableco (D-RAY). I only have personal experience with D-RAY (one of the absolute BEST guys you'll ever do business with, trust me), but I've NEVER heard anything but good from guys who have dealt with GARRYOWEN.

[url]http://www.sableco.net/[/url]
[url]http://www.cavalryarms.com/[/url]

The first generation Bushnell Holosight (manuf. by EoTech) had an interchangeable reticle system, but is an inferior sight than the gen. 2 one, and should not be considered solely on that basis (comparison info on page below).  The gen. 2 EoTech sights can be purchased with either the dot or the reticle, but not both.

Pics of gen. 1 sight at top and bottom, along with pic of reticle options.
[url]http://www.rushusa.com/html/products/eotech.html[/url]