Largely in the interests of rebalancing opinion, I'd echo the prof's views regarding differences between Blu-ray players. Likewise I respect others' opinions and would ask for the same courteousy, not that this thread has degenerated into anything approaching a flame war, at least not yet...
Having owned a Denon DVD2500BT for seven months and compared its Blu-ray performance with my PS3 on numerous occasions, I'd state emphatically that there is a difference, in terms of both sound and picture performance.
It may or may not lend credence to my views, but I've compared the above over a long period of time, with an array of Blu-ray titles. In my opinion, the difference in Blu-ray performance isn't just subtle, it's striking.
Of course we can debate why this may (in my opinion) or may not (in the opinion of others) be the case, but I'm most concerned with the fact that I can clearly notice a difference (as have family members and friends). This is all routed through my Yamaha RXV-1065 receiver and viewed on my Panasonic V20 plasma (alright, it's not a Kuro, and may not compensate for deficiencies elsewhere in my system to the same degree, but it's still a very good display)
As suggested above, don't simply accept accounts of uniform Blu-ray performance across buget and high-end models, rather audition some BDPs yourself to decide if it's worth the extra outlay.