mrandychen,
I commented in the Gladius thread where you asked for beam shot comparisons. I appreciate voodoogreg's vote of confidence in my ability to answer honestly and indeed, this would be my intent but given my vested interest and likely bias, my comments could and should be suspect to some degree.
That said, the Aleph 1 is clearly superior to the Gladius as it has a stranger name and I had my hand in its design! /ubbthreads/images/graemlins/crackup.gif
The truth will set you free and lies will bind! /ubbthreads/images/graemlins/nana.gif
OK, in terms of beam and output, the reflectors are close enough in photon redirection that any significant differences will not arise from them. (McR-27 is better; watch my nose. /ubbthreads/images/graemlins/tongue.gif ) The beams from these lights will depend much more significantly on drive current to the LED (or duty cycle in the case of the Gladius) as well as the bin and performance of the specific LED's.
The Aleph 1-2x123 is considerably smaller and shorter than the Gladius and it has considerably fewer functions and features regarding the light output itself. The Gladius is a professionaly manufactured light with presumed unlimited availablity and a warranty program. The Aleph 1 is very finite in number and will no longer be available at some point. It does not have any expressed warranty beyond the builder standing behind his work.
If the additional features and differences are not significant to a current Aleph 1 owner, it would seem that adding a Gladius to one's quiver would be of questionable benefit beyond the mantra of "buy them both". /ubbthreads/images/graemlins/icon3.gif
If one were in the market for a 27 mm based light and did not have anything similar, then the decision might be a bit tougher and the features provided by each of the lights as well as their strong and weak points would all need to be factored in. In addition to the Gladius, there are other lights hosting the IMS 27 including the LionHeart. One might also want to consider the Pelican M6-LED whose predecessor with its 27 mm reflector gave birth to the McR-27. Availability of the choices would also have a bearing.