Screw-caps are great. They work in to my KISS theory: Keep It Simple, Stupid. One product that will work whatever the scenario. On-trade, off-trade, it makes no difference as you can't go wrong. But, and there's always one of those, there is a cost. They're more expensive. Only a couple of pence, but it all adds up pretty quickly.
Crown caps are much cheaper, even the bottles for them are cheaper, but they're not suited to every environment. If the customer doesn't want to drink it now then they'd better have a bottle opener when they get to wherever they'll be drinking it.
A third option would be the ring-pull crown cap offering the convienience of 'open anywhere' with the usual crown-cap benefit of lower costs.
We've been speaking to a European manufacturer of these recently as we'd love to bring them in to the UK. No UK producer uses these at the moment, so the time is right for some small companies (like our customers!) to get in there first. Being small gives massive benefits in regards to flexibility. The great thing is that per-bottle it may well work out cheaper than using a standard crown cap!
Of course we'd need a new sealing machine, but we're happy to do that if we have the demand. We would ask for a small one-off contribution to assist towards the cost of the machine from everyone who bottles using it and then you can garner the PR and the massive USPs that go alongside being the first to use an innovative product.
Please, let us know what you think using the comments function, or give us a call to discuss.