DCR made a video about this when the Garmin Rally power meter pedals launched, so I knew it was possible. But, I hadn’t actually ever done the math around whether it would be worth it if you didn’t already have a set of Vector 3s laying around. Yesterday a friend of mine mentioned that he did exactly that over the summer; back when the Rally XC 200 were in short supply and no one was discounting, so it definitely made $ sense then.
Now, with discounts available the difference is only around $200. Still a decent sized number, but not so large that it is almost another set of used Vector 3 pedals. So if you want some quality SPD power meter pedals it’s worth asking whether the Garmin warranty is worth $200. For me, it might be. I haven’t had the best of luck with power meter durability, and I suspect that putting the PM in a place that is subject to significant abuse could exacerbate that. But, everyone’s value curve is different, so it’s definitely worth a ponder.