Not an issue unless you suffer from any anxiety problems related to balanced visual appearances in the brake disc department.
Zero perceivable difference in performance, long term crossed drilled can exhibit small cracks between holes if disc is given heavy treatment Sent from my iPad using Tapatalk
exactly this...even with my front disks all cracked between the holes..no noticeable drop of in performance. Now i have brembo HC blanks..exactly the same performance as drilled. all about looks. Same as grooves,apart from its known the grooves`cheesegrater` the pads,reducing there lifespan over a blank disk
It's not always as bad as you think... depends on the car There's some proper data somewhere, but I can't find it http://www.brembo.com/en/company/news/brembo-brake-discs-type-performance provides a basic summary