It really depends on the rate and not the drop. If you have a progressive rate spring then they will not kill your shocks as fast. If you have a static rate spring that will exceed the dampning ability of the shock then you will blow the shock.

You could theoretically run Sportlines w/ the stockies due to there fairly soft nature. If you are going for looks don't worry about it and just drop but if you will be running hard then the stiffer rates when the spring is compressed will kill the shock.

Hope this makes sense. Being tired at work sucks