umcelinho
Marcelo
I've tried a friend's 1.9 Ultron on my R-D1 quickly as soon as I got the camera. It balances well with the body, the speed is good enough and it's a versatile focal length.
I had his lens with me for a few days before I got the R-D1, shot a roll with it on my M6, liked the results.
Regarding the 28 Ultron vs the 35 Nokton, I think it really depends on what you like best. I'm more of a 35mm field of view guy, but I get away well with 50mm too. I've travelled with the R-D1, 35/1.4 SC and 12/5.6 a few times and it's a fantastic pair: one fast normal for 80% of the shots, one ultrawide for the remaining 20%. You've got to consider if the extra stop and smaller size would make a difference for you in use. In any scenario you'd be with a good lens option, though.
I had his lens with me for a few days before I got the R-D1, shot a roll with it on my M6, liked the results.
Regarding the 28 Ultron vs the 35 Nokton, I think it really depends on what you like best. I'm more of a 35mm field of view guy, but I get away well with 50mm too. I've travelled with the R-D1, 35/1.4 SC and 12/5.6 a few times and it's a fantastic pair: one fast normal for 80% of the shots, one ultrawide for the remaining 20%. You've got to consider if the extra stop and smaller size would make a difference for you in use. In any scenario you'd be with a good lens option, though.