No slams taken or given..... but the 28 Skater has more forward entry lift and as much constant section as the 30 Spectre (cut down 32 Skater). Peter changed his designs after the 24's and the old 32 and brought more bottom.....further forward. The bows on the old Skater 21's 24's and 32's were extended...The bows on the 40's, 46's, 36's, new 32's ......and 28's...... are not. Since greater forward entry area reduces the possibility of stuffing, I will take the new Skater design....over the old ......in big water for safety reasons. Basically, you have as much bottom on the water in a 28 Skater as in a 30 Spectre.....so the rough water capability should be very close..... But the edges on the strakes steps , chines, and transoms of the Skater are much sharper and more detailed than the Spectre/Motions (much more labor and sophistication in the Skater layup.....hence the price difference) giving better speed in all conditions.
I have run against some similarly powered Spectres and they are pretty stout....... but IMHO the driver means a lot in these mid sized outboard cat comparisons and a better driver will beat a less accomplished driver in either of these boats.