A wire loop is an easy target for the crew whereas the drainage pipe is much harder to hit. (I often need to help my crew aiming). The advantage of the drainage pipe is the pole sits higher and has less chance of catching your swimming aid in a gibe or tack.
As usual there are as many solutions as there are wayfarers. just go for what suits you and your crew best. What are you used to? I ask because spinnaker-ing is a team operation that needs training to get it fast and smooth. If you have a fast and fluent routine with your crew and current set-up, I suggest not to change it. If not, practice with your crew and try different set-ups until you find what works best for you and your shipmate.
– Guy hooks or barber-haulers.
– A simple clip on the shroud or a hook and cleat for halyard stowage.
– Bags or a chute (or laundry basket).
– A douwnhaul clip or a small drainage pipe at the inboard end.
– Manual pole system or a pole launching system.
– etc. etc.
Are you racing or cruising? A racer may choose the fastest ‘get and store’ solution whereas a cruiser may choose a more stable pole stowage, well out of the way of his swimming aid, cap or hat.