I have never had any issues adding and removing links with the mushroomed pins. I would only be concerned about this with Shimano chains which have pins you are only supposed to use once.

One thing Spot, make sure you carry some extra links and a chainbreaker with your tools/patch kit. Unlike a derailluer equiped bike, you don't have any extra slack and tensioner if you break the chain, so you'll need to install those extra links to avoid walking home. I squeeze them right in my patch kit, fits perfectly. Only needed them once on an MTB ride, but it was sure nice to have it.