DV stove or DV fireplace for primary heat source?

I need to retire an existing B-vent gravity wall heater and I know the prudent thing to do is insulate and install a DV gas stove heater. But I wish I didn't have to lose space to a stove. I only have around 890 square feet to heat. A Rinnai engineer told me one of their contractors could install a DV gas fireplace as the primary heat source in the home if the specified heat output is as great as the building heat load. In fact last month a contractor did a walk-through with a blower door test and Manual J calculation. If I insulate all around I can get the proposed design below 21000 BTU heat load. And California is giving pretty good rebates on insulation labor.

The Rinnai would be matched to this size house, it has several levels of modulation, and I trust the company. But it is not the most attractive DV gas fireplace. So here are my questions:

a) Do DV fireplaces that are installed by qualified contractors fail and start fires any more often than other DV appliances with quality installation? There will be permits and inspections and certified plumbers but I am thinking about the fact that that primary gas appliances sometimes turn on by themselves.

b) What if anything do I look for in a DV gas fireplace's description or specifications that indicate it's suitable to be the primary heat source in a home? Some DV gas fireplaces are clearly not suitable. The Rinnai is apparently suitable but I'm looking for other options.