Sometimes the missing piece is outside the glove you already like. The Outdoor Research Revel Shell XT Mitt is a shell-mitt option, so I'd compare it with that existing glove in hand rather than shop as though the two items were unrelated.

Nylon appears in the material information. The complete shell, seam, and closure specifications still need checking before assigning a particular level of weather protection.

The Focused Role

Shell-mitt format.
Nylon material description.
Revel XT product line.

Check what the manufacturer expects to be worn inside and how the sizing accommodates it. A shell that is comfortable over one inner layer may be awkward over a thicker glove.

Overlap Is Part of the Setup

The wrist connection needs to work with your jacket. Look at how the cuff adjusts and practice the intended overlap so putting the mitt on doesn't require a long rearrangement of sleeves.

The mitten shape also changes dexterity. Think about where you can comfortably use it and where small tasks would require something else. That isn't a flaw so much as a characteristic to plan around.

What Would Justify This Extra Piece?

I'd add the Revel Shell XT when an outer hand layer addresses a specific gap in a setup I already use. I wouldn't assume an item called shell includes the insulation of a complete winter mitt.

For someone who wants one grab-and-go glove for ordinary outings, a layered arrangement may be more complexity than necessary. For someone who values changing outer and inner layers separately, it can be a useful format. The decision should come from verified compatibility and construction, with the extra piece earning its place through a clear job.