Follow the manufacturers instructions please; not online anecdotes.

"When installing against a combustible surface, a minimum 5" (127) riser is required", and its a mix on if quartz is "non-combustible" some sites say it is some say resistant some say it won't burn but could melt at high temps...

I'm hoping for real world answers with rangetops specifically, since it's also clear alot of people use it.

Quartz is 80% plastic by volume and the manufacturer says you have to use a riser…

Engineered stone is not noncombustible.

“A 5” riser is required. “ VERY clear. Install the required 5” minimum backguard.

"Most of the quartz burn mark discussions I've come across online are specific to ranges"

Please say why you think the rangetop - with its six gas burners - would have a different or lesser effect on the Quartz than a range. Isn't it 6 gas burners regardless if it sits on top of an integrated oven (a range) or not (a rangetop)?

"some say it won't burn but could melt at high temps..."

Is one of those better than the other? Either way, it's telling you that Quartz should not be placed behind a heat source.

There are two fundamental directives here. One is that all the warranties from all Quartz manufacturers specify that it does not cover damage from heat from being placed too close to a heat source. Your Quartz is damaged from the heat, it's on you. The second is that you have specific instruction regarding a riser, and you are looking for people to say you can ignore it with a rangetop. That is not going to happen.

Sounds like quartz shouldn’t be considered.

I site the difference in rangetop vs range because the gas ranges have ovens venting heat directly against your backsplash vs the back burner flames not being directly on the backsplash with rangetops nor will it vent a oven.

Either way, I’ll just go with a natural stone.

Going with natural stone does not eliminate the requirement for the backguard. Understand the NFPA definition of a combustable wall.

*I’ll go with a non combustible wall.

That requires a block wall, or steel studs covered with cement board.

Brick Exterior wall

Steel studs

Cement board

Porcelain tile

I had my kitchen renovated a few years ago. I chose engineered Silestone Quartz, color: charcoal soapstone. I had the Silestone applied as my gas range backsplash for an easy to clean surface. My back-burners are simmer burners and are 8.5 inches from the Silestone backsplash. I cook from scratch, so my oven and stovetop get used daily. When I use the stovetop and oven, the backsplash remains cool. No issues. My backsplash looks as good today as the day of installation.