I'll chime in too-the Timberlines would be a great complement to your current lighter-weight pants. I have Kuiu Attacks and the Timberlines and I feel like I have any condition covered. I did find the knee pads in the Timberlines chafed a little so I took them out, but the waterproof seat and knees are awesome.
I have the Dehaviland they are nice & expand but they are a little noisy. They are designed backpacking pants. Don’t have the Sitka Timberline to compare with but I have the Kuiu guide pants and they are thinner no fleece backing but were comfy to walk in.