If you are nervous about the springs, an alternative to the tool rental route could be to buy the Klann clone spring compressor on Ebay and then re-sell it here for say $10 or $20 less than you paid for it. You get cheap use of the tool and someone else looking to buy one gets a bit of a deal.

I bought one and it's a well made tool and others on this site have spoken positively about it. They generally go for around $180 to $200.