The 3-5% penalty range is consistent with what other users have reported over the years but I'm sorry that I can't seem to find the threads/references so my response is unfortunately anecdotal.
More importantly, would you be interested in sharing your data? It would be great to feature it as a blog post and I'm sure a lot of users are going to be very interested. It doesn't have to be a polished write up and we've got other contributors who'd be happy to help with the draft if that's a concern. Cheers!
