A single-position climbing aid gives you one heel lift height—usually around 45mm—which is fine for mellow tours and moderate skin tracks. If you're mostly doing casual backcountry days with gentler approaches or established routes, it'll get the job done without extra fuss.
The tradeoff is versatility. When you hit steeper skin tracks, that single height might not lift your heel enough, leaving your calves burning. On flatter terrain, it might be too high, making you feel unstable and overworking your quads. Dual and triple-position risers let you match the lift to the slope angle, which is noticeably more comfortable on varied terrain.
Go with single-position if you're new to touring, sticking to relatively flat approaches, or prioritizing simplicity. Just know that as you venture into steeper or more varied terrain, you'll likely wish you had that second riser option. Most experienced backcountry skiers find dual-position to be the sweet spot.