I have extensive experience w/ set-ups on 5-axis mills
its all about the programming. If you got a good programmer
(exper'd w/ 5axis) thats most of your battle.
They are by nature not very strong machines, if you can
tool it up right a 4-axis horz. is IMO the way to go.
You can always add a rotary table to achieve your 5th.
If you need anymore input e-mail me, i'd be happy to help.
Peace