I've got ~230kms of trailing riding on the Sirius setup SS. I've settled on a 28T [oval] x 21T cog for gearing. It's a nice general purpose ratio that I don't mind cranking on flat/rolling terrain, but that I can turn over on most climbs. It also allows me to run the sliders in the shortest position I can fit a 29 x 2.6" DHRII and I love me a short CS. No plans on changing the ratio for the rest of the winter unless/until it snows. I've got a 28T x 24T option that may be needed for slogging through the white stuff. We'll see.
I'm really glad I made the swap to the Pipedream. Going from a good bike to great bike you can't wait to throw your leg over is amazing. I kept trying to love the old bike and it just didn't happen. The Sirius is a keeper for sure.
The SS experience has been good for my riding skills. I'm reading the trail better than ever and braking the least I've ever done. It'll be really interesting to see what happens when I get back on my FS bike come the dry season. The only downside to SS I can really point to is that it's not great when I am tired. I've had some back to back days of long rides/trail runs and riding SS on techy terrain without that top 25% leg power is so hard. Lots of sections I can roll through at full power with enough momentum end up as slow chuggy/mashfests. I just keep telling myself it's making me stronger.
I'm glad I finally tried SS trail riding. Since my urban assault bike is SS that's all I have been riding for a while now and it just feels natural to me.
I should also add the Tannus Tubeless insert in the rear wheel is pure GOLD. I liked it a lot back in Victoria, but now that I am living in Comox the trails are so much faster that the impacts on the rear wheel are impressive. I'd have a flat tire/damaged rim every ride without the insert. As it is I can feel the rear wheel getting worked hard and I do try and ride smoother lines/get the bike into the air, but it's just not possible to ride fast and protect the rear wheel fully. I was checking the tire/rim after each ride at first expecting trouble despite the insert, but I don't bother anymore. I think I'd be having 50% as much fun riding the HT without an insert as I'd be spending a lot attention on not flatting.