I don't know about the Candy pedals, but the Eggbeaters don't have a spring tension adjustment. They don't need it. They are easy to both engage and disengage. You never have to look to engage them because they are 4-sided. Accidental pulling out under hard pedalling generally isn't a problem (at least not for me or that I have really heard about for others). I know a guy who is an extremely strong cyclist who gave away his spd's and switched to Eggbeaters on all his bikes. He hasn't been pulling out of the pedals unexpectedly. Overall, my Eggbeaters have worked flawlessly for probably a couple thousand miles. When not engaged, I haven't had more trouble sliding off the pedal than I previously did with spd's.

I have heard that some Eggbeaters need to be rebuilt more often than other pedals. I understand this has been corrected with the mid- and high-end versions. However, like I said above, my first pair has a couple thousand miles and is still going strong. I wonder if the critical comments in this regard are overstated, or maybe it's somewhat dependent on how they are used (mountain vs road, etc.).

Maybe your Candy pedals were defective. It really shouldn't be that hard to unclip - should be almost effortless.