The EOS Tactical starts off in low mode first, or at least my older generation 25 lumen model does and that is one reason why I prefer it to the standard EOS. The Tactical also has filters for use in red, blue, and green and with the older spot only beam profile, the lenses worked great as a diffuser, especially the green one and the green was so soft, I sometimes forgot that I had the cover filter over the optic.
So basically, the newer 45 lumen Tactical EOS should also start off in low mode unless they changed that feature on the newer version. Why is the Tactical 45 Lumens and the standard EOS 50 Lumens, well, you got me but I wouldn't be suprised if it were just an error on their site and I recall from a previous email to PT, they said that all EOS models have now been upgraded to the frosted optic with the Rebel Led. Personally, if I were you, I would call PT just to confirm that the Tactical comes on in low mode just to be sure and let me/us know because that is the best feature of the Tactical IMHO because since they frosted the optic, I am guessing that the flip up lenses won't be so necessary due to the difuse spot of the new optic unless you want or need the colored lenses.