Old thread, but I’m loving this suspension post with my xpress. Rated for 264lbs, but that’s underselling it. It has an extra spring you can add in for heavier riders that really ups the stiffness, but still has great give. The design is way more seriously engineered than Lectrics generic style spring post.

The 31.6/450mm long is what fits my bike with the lectric stock seatpost clamp.