Yeah, I would. Most major mods are still adjusting to fit into the 1.9 environment, some STILL haven't left 1.7.
If MC is going to keep coming out with new versions quickly, it's going to be pretty tough to maintain a good, up-to-date server.
I think 1.7.10 is going to go down in history as a golden age of mods for Minecraft 1. There's a huge number of great mods, they're stable, and they're documented.
I still haven't made the move off of 1.7.10 for my SSP. Just not ready to give up all of my tweaks and I like Thaumcraft 4 a bit better than 5.