A steel krab will last longer but will then start to wear the attachment hole on the Basic. Stick with your alloy one, what you're seeing is just more obvious as it is a new device, I've not ever needed to chuck a Basic out because of the hole wearing with an alloy krab. I guess if you have a small diameter krab, like a Grivel Plume, that may show wear faster as there is less metal at the contact point. Some krabs are a softer alloy than others. If I use DMM oval krabs on hanger plates then the steel hanger cuts a line in the krab and I need to sand them down. I don't use DMM for caving any more for that reason. My Petzl krabs don't have the same problem. If you want to give your kit the best chance of a long life, clean kit regularly and if possible use a connector of the same manufacturer as the alloys may be a similar hardness. Total theory that, nothing based on fact, but Petzl Basic + Petzl OK Oval has been fine for me for a long time.
