OKC would have had the same problems under the old system that they have under the new system. If you treat the luxury tax line as a de facto hard cap, and have 4 players simultaneously requiring max or near max contracts, the consequences are the same in either system.
The Spurs, otoh, would have been able to keep their big three together under the current system. Their key players didn't reach peak earnings at the same time and the Spurs never had more than one max player at any given point in time. They won the le in 99 with Duncan still on a rookie contract. They won in 03 with Parker and Manu both on initial deals. Robinson retired in 2003. Manu's second contract kicked in for 04-05, but his salary that year was less than half of Duncan's salary. Parker was on the last year of his rookie contract in 04-05. With Parker's new contract about to kick in for 05-06, the Spurs salary dumped Malik in 2005 and Rasho in 2006. The Spurs were also willing to go over the tax line by small amounts in 3 separate seasons.
From 05-06 thru 08-09, the Spurs retained room of about 30M between the combined salaries of their big three and the luxury tax line to field a supporting cast. When that room started to shrink as they approached the 09-10, the Spurs busted through the tax line to make the RJ trade. That is the one transaction that the new system would likely have prevented the Spurs from executing. Too bad the new system wasn't around then.
I did some analysis related to this subject almost 4 years ago. For anyone interested, it can be found here:
http://www.spurstalk.com/forums/show...=1#post3358978