Here's a chart of home/road splits through 2011-12, and including Roy's entire career.
Player|H Min%|H SV%|R SV%|H SOG/60|R SOG/60|SOG Dif|SOG Dif%
Belfour|53.69%|.904|.909|25.33|28.21|2.88|11.37%
Brodeur|50.90%|.911|.915|24.28|27.03|2.75|11.33%
Burke|50.22%|.905|.898|28.73|31.47|2.74|9.54%
Hasek|52.20%|.925|.919|27.81|28.88|1.07|3.85%
Joseph|52.80%|.909|.903|29.08|30.48|1.40|4.81%
Lundqvist|53.93%|.920|.920|26.94|30.04|3.10|11.51%
Luongo|53.78%|.921|.917|30.35|32.18|1.93|6.32%
Osgood|51.70%|.904|.907|25.40|27.19|1.79|7.05%
Roy|55.50%|.911|.909|27.02|29.77|2.75|10.18%
Vokoun|51.84%|.923|.910|30.79|30.64|-0.15|-0.49%
The higher the Dif the more likely, and stronger the home under-counting influence, and the lower the more likely, and stronger the home over-counting influence. There is an "era" variance in SOG/60, H/R difference, and SV% which makes the career values less than ideal benchmarks, but it stands as an illustration that there is something to investigate further.
Brodeur's Dif% has dropped slightly over the last two seasons, while Lundqvist's has jumped from average-ish to the top of the list.
Using the H/R split data from HockeyReference here is the league average SV% for
1988-89: Total: .879 Home: .880 Road: .878 Dif: .002
1989-90: Total: .881 Home: .884 Road: .878 Dif: .006
1990-91: Total: .886 Home: .891 Road: .881 Dif: .010
2006-07: Total: .905 Home: .907 Road: .903 Dif: .004
2007-08: Total: .909 Home: .910 Road: .908 Dif: .002
2008-09: Total: .908 Home: .911 Road: .907 Dif: .004
2009-10: Total: .911 Home: .914 Road: .908 Dif: .006
2010-11: Total: .913 Home: .914 Road: .912 Dif: .002
2011-12: Total: .914 Home: .916 Road: .911 Dif: .005