what's the worst that could happen if there's a hole in the A/C evaporator hose???

 

The refigerant will leak out.
The POE oil will absorb a lot of moisture, the whole system will need to be cleaned of this oil. Will need to replace the line, drier, oil, refrigerant at least.

PS it's porsches, not porches.

 

Actually the oil doesnt absorb moisture, its the desiccant in the accumulator. The system can be exposed to the air/moisture for about 24 hours before the desiccant is rendered usless. Therefore the line and accumulator need to be replaced, then the system vacuumed and recharged.

 

Yes the drier will absorb moisture too.
I'm universally certified for the handling of all types of refrigerants. During the classes they show the POE oil in a beaker sealed to a beaker of water in a sealed lab room with consistant temperature. In less than 12 hours the POE oil sucked all the water into it.
When we do home a/c with POE oil we purge nitrogen through the lines the whole time they are open to keep air out.
Ambient air contains moisture.
Mix moisture, and POE oil and it will coat the inside of your evaporator, condenser and reduce the efficiency of the a/c system.
Remember no one liked r134a when it first came out, and NO ONE gets good results with a retrofit kit, it's because of this barrier that reduces heat transfer.