I still have trouble with all the 1.8 stuff because minecraft was in 1.7 for so long xD and as people have said; the wings- rare or not- could definitely affect the amount of donations, thus also affecting the running of the server.
Some blocks are left out for a reason, but when the update does come to the server, I agree all the remaining and possible items from 1.8 they can add should be added. But when the server decides to update again (probably ages judging from the 1.8 update) all will be explained And I do imagine that wings will be illegal, not rare. Myself as a donor, there would be a lot of anger if wings were not illegal.
I support, adding 1.9 would be good except the wings like Demon_Umbreona said before. If you had to buy the wings as a kit or get them with diamonds at /warp grass it would maybe make it better.