It doesnt matter if they are voiced for guitar or PA. Either way, guitar will be fine. PA is just going to power the signal and not colour it.
Technically that is correct, but the point of having a good guitar power amp is that it WILL color your tone in a positive way.
One other thing to keep in mind... if you are using a modeling device (Pod, Tonelab, Boss GT, GNX, etc) with built in speaker simuation, it was designed to sound good through a "flat" power amp, like you'd use for a PA system.
But if you're using a dedicated preamp (MP1, Triaxis, JMP1, etc), they are designed to be used with a guitar-oriented power amp. Is it something you can overcome with EQ? Most likely. But you'll most likely be up & running more quickly with a power amp that was designed for guitar. Thus my reco to look at the Peaveys, Carvin T100, Mosvalve, etc.
I've gone through this twice in the past... once when putting my JMP1 rig together and once when putting my RM4 rig together... both times the preamp arrived before the power amp (a Mosvalve for the JMP1, a Carvin TS100 for the RM4) and I tried to fill the void by using a Carvin HT150 power amp. While it technically worked, it just lacked the feel of a power amp desgined for guitar.