I purchased some Vector 3 Garmin pedals a couple of years ago for my road bike. The last few years I have concentrated on MTB and Gravel and haven't ridden my road bike at all. I discovered these Rally conversions and jumped right on it. The conversion labor is simple, about 30 minutes tops and I now have a second pair of Rally 200's. I now have them on my hardtail MTB, and my Gravel bike. Both perform the same and as far as I'm concerned they are a must have.
It was with hesitation that I purchased the Rally XC Pedal Body conversion kit to migrate my road power meter pedals to my gravel and mountain bikes. For gravel and mountain biking I have been a lifetime user of Speedplay Frog pedals (now discontinued). But after several knee surgerys I appreciated the unencumbered float and secure release/retention that these pedals offer. I have used Shimano SPD off-road pedals many times before, they perform well, but did not compare to the extra float found in the Frog pedals. With this in mind I purchased the Garmin Rally XC conversion kit and the Shimano SH56 SPD Cleats. These cleats offer 6 degrees of float compared to the 4.5 degrees of the standard Garmin cleats. It sounds like a small amount but made a world of difference allowing greater freedom of rotation, reducing the stress on my knees. The combination works extremely well and best of all I now have power meter data for my gravel and mountain bikes. I could not be happier!
I've been waiting for Vector 3 power on the SPD-SL platform. I had converted my vector 2 pedals to Shimano pedal bodies with the Garmin kit and some Shimano pedals. Once I upgraded to Vector 3 it was back to the KEO platform which I don't like. This is a pretty easy install and only took about 30 minutes to complete. The Rally pedal bodies have metal threads vs the plastic threads on the Vector 3 pedals. I plan on buying a set of the xc pedals for my cross bike. It's easy enough to change them as needed for the cross season.
Reasonably straightforward to swap over, and a good fit with Shimano cleats (although, not as precisely snug as original Shimano pedals). You'll need a 22mm socket that's slim enough to fit inside the pedals - a Tekton brand one worked for me (SHD22122).
I had initially purchased the Garmin Rally XC200 pedals and were very pleased with them. So I purchased the conversion kit. The process of converting is easy and straightforward. I had been using Powertap P1 pedals and like the Garmin's a lot more.