The factors you're asking about are the reason for the recommendation to use cruiseline services for excursions. Even if they have a 99% on-time record, it's that 1% you're avoiding by being on the safe side. Also the tour opperators the cruiselines use are screened. If they get complaints or have repeated issues with them they replace them or cancel their contracts, there is a performance clause. If you use an outside company, there are many. They may be the best experience ever. They may be the same company the cruiseline uses in some cases but less expensive to just go direct. After you've used an excursion company once and you like what you find, you can take their card or name and # and use them the next time. You can cut out the middle man (cruiseline) that way. But for a first experience at a port to randomly choose someone because they have good pricing and a colorful website is risky. Is it worth the difference in cost to take the chance. Only you can decide that, there is no BBB to check with on these ports. Some people on this and other sites can tell you of their experiences but there is no guarantee you'll have the same experience. The risk is probably small that you'll miss the ship or have major issues. Just for peace of mind alone, it would have to be a really major cost difference and I'd have to have some folks I trust recommend the opperator for me to take the chance, however small the risk.