Or Nikon, for that matter - their Toshiba-sensor bodies are the worst I've ever ever seen for banding.
They don't use such sensors anymore. If one was concerned about doing massive pushes with no banding, I don't see why Nikon wouldn't be on the list. Now that their latest cameras behave with very good grey linearity (ie, colours stay accurate - which IMO is just as important as noise when pushing files), in most softwares, I would very much recommend it in fact.
Beta versions of Lightroom doing suboptimal RAW/DNG conversion for new cameras.
Adobe has frequently put out rubbish profiles for cameras, but I don't think that there's a single case where banding behaviour was affected by Lightroom's support being in the beta phase, or by using DPP vs Lightroom vs Capture One vs etc.
The photo below comes from the file I linked above, from the 5DIV - so very much not in a beta phase - pushed in DPP, LR and C1. The banding pattern is the same regardless of the software.
All that said I wouldn't worry that much about low ISO banding with the R unless you're routinely pushing files by more than 2-3 stops.
I would worry a little bit more about what you can see at high ISOs as this should be within the "ISOless" range of the camera, where it makes sense to underexpose by using lower ISO values, to preserve highlights, and push in post, with supposedly no penalty to noise quantity. If Jared Polin's 10 000 ISO shot is any indication, the R may exhibit mild banding with much smaller pushes in some situations.
banding shouldn’t really be an issue anymore
Sadly it still is
. I've had various problems with banding, even recently. I had to have my 6D exchanged after a botched repair because the sensor had started to exhibit very noticeable vertical banding. Apparently there's a software calibration step required at the factory / during repairs to eliminate banding related to the ADC design of this camera and mine could no longer be calibrated for some reason. The replacement still has one vertical band 1/3 through the frame
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Canon isn't an exception. As Keith_Reeder wrote, some Nikon cameras, for example, had horrible banding (D7100 comes to mind). My Ex Fuji X100 (the first one) had a noticeable banding problem as well.