Baranyi, I would concur with Ecclectique concerning the Berning. So far as purchasing new over the prototype, the concern would be that the prototype may have been sitting in a box for years if you are not purchasing from a user. Be CAREFUL of this. I would be concerned about the capacitors which may or may not be in need of replacement which would then add to the cost of the amp and may not make it worth it over new. If the amp is operational and is guaranteed as part of the sale, this would be an option. The price should be commensurate with these factors.
There really isn't much risk if you have 4.5K to spend. It is a versatile amp that can work with many loads and since the amp is in short supply with a healthy demand, it insures the value will be maintained. It sounds to me that you really need to hear it first before committing. You should probably search out a user in your area. There are few products in this hobby that I feel comfortable recommending. With certain considerations in mind the zh270 is definitely one.
There really isn't much risk if you have 4.5K to spend. It is a versatile amp that can work with many loads and since the amp is in short supply with a healthy demand, it insures the value will be maintained. It sounds to me that you really need to hear it first before committing. You should probably search out a user in your area. There are few products in this hobby that I feel comfortable recommending. With certain considerations in mind the zh270 is definitely one.