I had the Sonder frameset for a while, built up with straight bars and Alfine 8 hub. Used mainly as my Deliveroo bike.
https://yacf.co.uk/forum/index.php?topic=17.msg2445390#msg2445390it was what you'd expect from a good quality steel touring frameset, not excessively heavy or the staid handling some touring bikes have. The tyre clearance (700c) was a disappointment, I was under the impression 40mm would be fine, but 35s were as large as I felt suitable. Otherwise I couldn't fault it, I didn't keep it long, though that was due to my usage changing rather than the bike.
Sonder/Alpkit were as always a pleasure to deal with, though in normal times you'd wait a week or two for them to have another sale rather than pay full price.
I don't know anything about the Spa, though if I was looking there and heavy touring wasn't on the agenda, the steel Elan would be on the shortlist.