I just inherited a croll ascender and was wandering if it is reliable for a self belay system, or should I ditch the thing and go for the basic?

According to Petzl's instructions for the device, which can be downloaded as a PDF from their website, the Croll is approved for toprope soloing. You must add the chest piece of webbing to keep it vertical. The problem with the Croll, however, is that it is designed for usage with a seat harness that closes with a half-moon quick link. This is how most caving harnesses work and the Croll is perfect for setting up a Frog ascending system using that harness. You'll probably find the Basic works better with a rock climbing harness when attached with a locker, as it will be oriented correctly.

Thanks Tim I think I'll get the basic.

Happy climbing