If I remember correctly, the reason that some Shall-Issue states do not honor permits from other Shall-Issue states is because the guidelines for a CCW permit differ in the other state.
For example, let's say one of your home state's guidelines for a CCW is at age 18+, whereas the state you're traveling to shall issue only at age 21+
As for Open Carry...
Permissive Open Carry States - A state has passed full preemption of all firearms laws. They permit open carry to all non-prohibited citizens without permit or license. Also open carry is lawful on foot and in a motor vehicle.
Licensed Open Carry States - A state has passed full preemption of all firearms laws. They also permit open carry to all non-prohibited citizens once they have been issued a permit or license. Also open carry is lawful on foot and in a motor vehicle.
Anomalous Open Carry States - In these states, open carry is generally lawful, but the state may lack preemption or there may be other significant restrictions.
Non-Permissive Open Carry States - In these states, open carry is not lawful, or is only lawful under a limited set of circumstances, such as when hunting, or while traveling to/from hunting locations, while on property controlled by the person carrying, or for lawful self-defense.
As the map shows, seven states and the District of Columbia fully prohibit the open carry of firearms. Additionally, there are eleven states which permit open carry without requiring the citizen to apply for any permit or license.
Disclaimer: While state law may not prohibit the open carry of loaded firearms, it is not uncommon for law enforcement to be unaware of this fact. Especially in states with highly restrictive laws regarding firearms ownership, open carry, even though legal, could result in serious negative consequences.
http://en.wikipedia.org/wiki/Open_carry