It'll depend on installation instructions but usually with a gas range it needs to have a bit of space in the back for the gas hook up.

My gas stove sits out from the wall by about 2 inches. It has controls on the front so we had a narrow piece of granite cut to go behind the stove so there wasn't a gap back there

Your cabinets are 25 Inches deep, inclusive of the door and drawer faces?. Stop agonizing? The range door and and handle usually sit proud of cabinet faces on gas ranges.

PS........ The Monogram duel fuel range is a literal MACHINE. I'd go look at one before I bought the Thermador. I have no client who doesn't love the Monogram. Not one. Top and oven both.

If a 3/8 or a half inch affects comfortable clearance at island? Then your island perhaps, should not be there .................. as is often the case.

Thanks, Afritzier--maybe we will try to do that to cover the gap. Thanks, Jan--we aren't remodeling so i can't move the island. Also, the Thermador Pro Harmony is intended to be flush. The 3/8 would not really be the concern--i misstated. I am more concerned with the space behind the unit. I think we will either put something behind to cover gap, as Afritzier suggested, or go with the Wolf, which fits the dimensions better.

You need to read the installation instructions including the Gas and Electric Supply Clearances section.