Unpowered reradiators with p25?

[Mycroft]

I've gotten conflicting information with regards to unpowered reradiators and p25 radios. Some people tell me that it won't work because of unspecified reasons, other people tell me it will work simply because it is literally reradiating a signal from one zone to another.

I only have a basic understanding of radio theory, and google isn't giving me much on this specific subject.

My problem statement is as follows:

I check in on a net every week and when I do so, I am generally in a metal building that stops radio signals cold. I started researching unpowered repeaters/reradiators and they appear to be a solution to this problem I am running into as I can set one of these up temporarily (and later permanently if the proof of concept works.) But sometime in the next year or so we are likely to move to p25+encryption.

Is there any reason p25/p25+encryption would fail in this circumstance I outlined? I'd like to know in advance before I spend any time/money on trying to make radio check-ins and training easier.