Persona and experience

Ok, I have a question about the reputations you get from the Persona supernatural ability (societates p90).
The text says that you put one xp in each of those reputations for every xp you put in Persona. Can you also get experience in those reputations via normal means? Such as living in a village, performing noteworthy deeds and so on? I think that would be reasonable, but I see a problem: normal reputation needs some care or it drops in time and is linked to a place (where the character lives, usually), while Persona reputation is instant, permanent and independent from the location. It's a mystical effect much similar to the various "Aura of...". How do you manage this difference? Do you keep records of the two kinds of xps and have different reputation values for different situations? Or am I missing something?

Also, the description of the Persona ability says that the disguise is always succesful, without need for rolls. So when do you actually need to use the score of the reputation? When is it rolled?

Thank you,
Matteo.

Or maybe the Persona reputations give you the appearance of a character, but are not actually reputations. That is, people don't know stuff about you, they just believe you are what you say you are. In this case, for instance, the magus Jim could have a Persona reputation "Henry" with his own reputation "merchant". Nobody would doubt that Henry is Henry, but people would need a reputation roll to know facts about him being a merchant. "Henry" would gain xps when his Persona ability did, while "merchant" would get it with the normal rules.

EDIT: I think the Persona's reputation isn't a reputation in the traditional sense (people don't know stuff about you), but has the effects of reputation (people trust you, or fear you, or want to make love to you, according to the reputation). Still you'd need to know a specific person well to offset the Gift malus with your reputation, I guess. It wouldn't work on strangers.

The insert box in HoH:S p89 says you need to roll Stamina+Persona difficulty 9 to make the change. Also, you have one disguise per point of the ability. Therefore, if you need more disguises you need more points in the ability. The rules on page 90 say for purposes of dispelling the equivalent spell level is five times your persona ability, so if you want it to withstand winds of mundane silence cast with enough penetration to get through your Parma, you want a good level.

Oh, yes, you're right. Although the roll to change identity doesn't seem like a big deal. In most cases you aren't in a hurry and thus can take your time to reroll until you succeed.