Comparison of Y₅₀₀ from extraction using the baseline pressure profile with that from the best fitting REXCESS cool core and morphologically disturbed pressure profiles given in Appendix C of Arnaud et al. (2010). Cool core systems are marked as blue stars, other systems as black dots. Top: universal pressure profile vs. cool-core pressure profile; Bottom: universal pressure profile vs. morphologically-disturbed pressure profile. The trend with R₅₀₀ is due to the inability of the Planck beam to resolve different profiles at small angular size. The effect is small (maximum  ~10 per cent) and quasi-symmetric (as expected), so no bias is introduced.