I have one slinki and it leaked at night whereas the standards don't! It's not as high in the rise and doesn't seem to fit as snug without the cross over tabs. Flynn leaks at the front top so I need a nice high rise though.
On the site they say it is more a daytime nappy because it's a trimmer fit - but it's still as bulky as the standard so might be hard to get clothes over! I just keep mine as a spare for in the house.
Also there is less room for adjustment as the tabs meet rather than cross over - so no good if it's a wee bit big. Not a problem for Flynn as you can see (large Slinki) -