Here's where I'd go with this:
Some bikes have higher quality forks than others. If a manufacturer does an "R" version and throws Ohlins at the bike front & rear, I'd expect those components to be better than the ones on the standard bike. Each manufacturer, however, has a range of products to suit your budget and as others have said, some Ohlins components have been built to a tighter budget than others (the XJR SP versions have already been given as an example).
Showa make the standard SV forks, and were responsible for the front forks of the Honda RCV up until the last couple of seasons. What price point, springs, shims and other settings the manufacturer has decided on probably make a significantly bigger difference than who made the fork.
To some extent there's a bling factor. Yamaha, Triumph or anyone else could make an R version with KYB components, but they tend to choose a big name manufacturer like Showa or Ohlins to underline that this model has different components, and is worth a premium.
Those are my thoughts, I'm no kind of guru but I'd say for most of us if you had decent cartridge forks, setup would be more important than brand. A good suspension company should be able to set forks up to suit with conditions other than smooth anyway
Jambo