I have the PP296 which were at or near their top of the line until fairly recently. I get in and out very easily so I guess the 5.1's might be just harder to unclip. I've been using Looks since 1990 and have always found them to be easy.
FWIW I just rode my old style Campy SG Record clipless pedals for a few miles. Now, talk about hard to get out of....
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“Life is not one damned thing after another. Life is one damned thing over and over.”
Edna St. Vincent Millay