Pretty much any aspect that is close, is felt strongly.. the closer the better.Personally, I think out of sign aspects can be felt with the same intensity as in sign aspects. Different astrologers have different opinions on out of sign aspects. Like Nove said, some astrologers argue it brings a different energy to the aspect..so in your case the aspect would still be considered a sextile - positive.. but with some negative –square- overtones. Other astrologers dismiss out of sign aspects all together.
In my experience there's no noticeable difference between -in sign- and -out of sign-.. If the aspect is close, it is felt just as strongly.
The reason your moon is sextile her moon, is because a sextile is a 60 deg aspect.. 26 Sag is 4 deg away from being in Capricorn, which would sextile Pisces by both sign and degree.. Or, on the other hand 1 Pisces is 1 deg of being in Aquarius which again would sextile Sag by both sign and deg.
The orb for your sextile is 5, which isn't a very close orb. You might feel this sextile with her, but it probably won't be the aspect that defines your relationship.. not because it's out of sign, but because it isn't all that close. Regardless of this though, I think you can pretty much look at your moons as simpatico rather than squaring..