After receiving advice on building a LED light setup I am down to ordering the LEDs. I cannot find a "reasonabe" price and time frame on any LEDs except from Cutters (in Australia). They currently only offer the XP-E in Blue and Royal Blue, not theXR-E. Is the XP-E better then the XR-E? Will I need less of the XP-E than the XR-E? Tank will contain SPS and Clams.

the output is pretty similar and currents are about the same and whatnot, however you will not find wide optics for the xp-e as far as i know so if you need optics wider than 40 deg you might wanna look for xre elsewhere

The tankis 48" in length and I was going to run 3 strips of 18 LEDs per strip. So 40 Degrees seemed alright. Should I be rethinking that?

Optics should be defined by your tank height and stocking requirements.

for a generic 10g aquarium, would you need optics? for softies, lps and possibly sps. and what would be the chances of a clam surviving without optics?

no optics required

its enough light for a clam but theres more to coral and clams than light

Tank height is 20". SPS and LPS corals will be in the tank. I plan on also having two anemones and 1 clam. I am concerned that the corals and clams at the bottom will not receive enough light without optics.

you can try 80 degree which means you will need to go with xr-e if you want that, otherwise maybe xp-gs can just put out enough light to punch it to the bottom without optics.