This is really scary news for consumers wanting to purchase a telescope,- because Wavefront Errors accumulate. If the Main Mirror has an RMS Wavefront Error of 1/14 at 633 nanometers and the Secondary Mirror has the same RMS Wavefront Error, the telescope will have a total wavefront error of 1/14 + 1/14 = 2/14 = 1/7 at 633 nanometers. This is the equivalent of a P-V Wavefront Error of 1/2 at 550 nanometers, which fails the diffraction limited criterion by a whole order of magnitude.

In fact if the Main Mirror just meets the diffraction limited criterion, then there is no quality fine enough for the Secondary Mirror, that will allow the telescope to possess a diffraction limited rating.

Now one might ask: Do any of those fine looking telescopes advertised to have diffraction limited optics meet the diffraction limited criterion as a whole system?  To meet this criterion, both mirrors must have an RMS Wavefront Error of 1/28 @633 nanometers or a P-V Wavefront Error of l/8 @550 nanometers.