does a reliable power vent hot water heater exist?

A couple parts in my A.O. Smith Power Vent Design GPHE-50 hot water heater have failed. I don't have the parts cost yet, but the fellow estimates they will cost $700-800. As it is seven years old, it probably makes more sense to replace the whole unit.
I need a direct vent. I have no flue available. It is 50 gallons.
Looking at Amazon for what units exist, I find reliability issues posted for every one I can find. Some more severe than others. Are there any of these units that are reliable?
Don. www.donwiss.com (e-mail link at home page bottom).
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On 12/7/2015 6:05 PM, Don Wiss wrote:

Given the seeming high cost of these units and their repair parts, have you considered an electric water hearer? You'll have to factor in the initial cost, estimated life, and comparative utility (gas vs electricity) bills to determine if it is worth your bother to continue with gas.
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Only to unconsider them quickly. Electricity is very expensive in NYC. Natural gas is so low to be almost free. I have tenants that use a lot of hot water.
Don. www.donwiss.com (e-mail link at home page bottom).
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On 12/8/2015 9:57 AM, Don Wiss wrote:

I'd suggested to get a couple more quotes. I now see you're in NYC, which helps explain why your quotes are expensive. Everything is expensive.
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To further complicate your suggestion I would need to get ConEd to bring in new wire from the street. That would take months. The wire now is what my electrician calls temporary. I think he estimated 6 gauge.
Don. www.donwiss.com (e-mail link at home page bottom).
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I got some prices. The warranty on my existing heater is six years. The parts costs are (with labor): motor $713 pressure switch $190 total $903
The same high efficiency unit is $2875. The regular one is $1895. And it will come with a 10 year warranty.
With natural gas prices so low a high efficiency makes no sense.
I have a choice of Bradford White or AO Smith for the same price. Model numbers not yet available. The HVAC guy (who is also my plumber) says the two manufacturers are the same. Are they?
Don. www.donwiss.com (e-mail link at home page bottom).
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