You've recently been to Grundlsee, yes?
We haven't been to Tirolensis, have stayed at both Grundlsee and Bellevue. While Bellevue was also in a beautiful spot, IMO you'd be hard-pressed to find something that equals Grundlsee for setting alone - if you were as taken with that setting as I was. For me, location is #1, and as long as the accommodations are attractive and comfortable and don't detract from my stay, I'm a happy camper.
So far the Mondi resorts do seem attractive and comfortable, and complement their settings, so we were pleased with both. I checked to see where Tirolensis is, and it looks to be close enough to areas of incredible beauty, and gets good reviews on RCI. We did stay in Selva di Val Gardena in the midst of the Dolomites, and you can get there from Tirolensis. Our resort (different trip, not a Mondi) was disappointing and I wouldn't recommend it, but IMO the location was unbelievable. Once we got there, we only wanted to hike and drive thru mind-blowing scenery, and gave up all thoughts of touring historic towns etc. like we usually do. So it depends on how you envision spending your time (and time of year).
There are a couple of rated resorts that are closer than Tirolensis to the areas I liked best, but not many. (I have my eye on one for the future maybe - BUT it doesn't have a kitchen which is a big deal. I would absolutely return to the area though.)
You can check RCI's map for location - I like to look at the hybrid maps to show me where the highest mountains are, and if you pan to the right from Tirolensis, you'll see the highest Dolomites are - between Cortina and Bolzano. Tirolensis appears to be in a valley, so driving would be pretty quick.
Anyway - I probably wouldn't hesitate to confirm into Tirolensis, especially if you want a mix of regular tourist things, along with just hiking.
If perchance you're thinking about a skiing vacation, someone else will have to address that - though our location in Selva de Val Gardena seemed beyond perfect for that.