Not a completely on point answer to your question, as I have no experience with the Romanceur and haven't ridden a Saluki.
That said, I did briefly own a (2nd?) generation canti Lightning Bolt and found it be fantastic. Mine was the root beer colored one. I can compare it to the canti braked Velo Orange Polyvalent and the Soma Grand Randonneur, both of which are 650b, low trail 'competitors.' The LB ride qualities were a step above both. It was noodlier than the VO by far, and didn't give me any shimmy issues as the Grando did (both with needle bearing headsets). Although not lugged, the welds were extremely nice and I found the finish and paint to be very good. I'm significantly over the weight limit for the original LB frame and had zero issues. It was flexy, yes, but not problematically so. The best comparison I can give is to a 650b Fitz Cyclez Randonneur that I briefly owned. That bike was extremely nice, lugged, and used Kasei fork blades, which were too flexy for my taste. (Again, I'd have been heavy for the bike). The LB was my favorite out of the three, with a smooth (maybe even 'planing' ride quality). I didn't keep the bike long as the friend I purchased the bike from had second thoughts and I agreed to sell it back to him. The lighnting bolt is a great bike, and since other mass produced 650b low trail bikes are few and far between (Kogswell, Boulder, and Box Dog Pelicans being available only used and sporadically) I'd recommend it without reservation.
Turning to Rivs, while both are 700c and mid/high traiI, I can also compare the lightning bolt to a 2000 Toyo Atlantis and a 2015(ish) Sam Hillborne. The handling differences between low and high trail bikes make any comparison apples to oranges, but the LB was significantly flexier in terms of tubing than both, as you would expect. I'd guess that the LB is going to have thinner tubing and a flexier ride than anything Riv has produced outside a lighter tubed custom or possibly a Roadeo. (Not a knock on Riv, just that I think the priorities are somewhat different). I've read that Salukis have somewhat tight clearances and make it difficult to fender 42mm tires relative to the Canti Bolt, which had more than adequate room.
Hopefully this somewhat rambling almost comparison is of use, and good luck in your search.
Brett in PDX