I run the Wrathchild 27.5 x 3.0” studded tires on my trail bike in mixed conditions and on packed snow trails and would very highly recommend them. They have excellent climbing and braking grip with the trade off of higher rolling resistance (and price!). They absolutely monster-truck up climbs. The 29 x 2.6” should have a very similar contact patch size. 2.25” will be way too narrow for anything but road riding, shallow snow (<10cm), or ice. The Wrathchild tread pattern is the best I’ve ever used for hard cornering in snow, minimizing self-steer and helping to pull the front wheel back onto the packed track when you steer a little too wide and end up in the soft edges. They are directional as well, so you can mount the front for braking traction and the rear for climbing grip. For mixed conditions the standard concave stud option on the 60 TPI version is probably most suitable, as the XL studs on the 120 TPI casings are more prone to tearing out when braking or cornering aggressively on hard surfaces. Just installed a pair of 27.5 x 4.5” Wrathchilds on my new fat bike too. I have no experience with the Schwalbes, but the linear block pattern looks similar enough to the terrible stock fat tires I just swapped out that I’d be worried about similar self-steering and cornering traction issues with those. Obviously these narrower trail tires won’t give enough floatation for all winter conditions, but they do greatly expand your options for winter ripping when the temperature and snow conditions are right. I find them best between -2 to -8 Celsius on groomed/boot-packed trails or snowmobile tracks. Any warmer, they’ll start to cut too deep and spin out. Colder than that, the snow tends to be too sugary to get good grip unless the trail is very firm already or the grade is more mellow.