I use the following mods in my client on a vanilla server and really do miss these in this modpack:

Essential (in my opinion):

• MAmbience - big mod ~40MB
• Falling Leaves
• Mouse Wheelie
• Sound Physics Remastered
• 3D Skin Layers
• BetterF3
• Presence Footsteps
• Sheep Consistency
• Giselbaer's Durability Viewer
• Extra Sounds
• Drip Sounds

Optional/Opinionated:

• Inventory Spam
• LazyDFU - Feel like it doesn't do much but it might do!

They are all updated and work in my patched modpack (I think 1.2.3) instance.

Most of these are client side, just add them yourself if you want

LazyDFU is in the pack already... As for at least half of those, they have a performance impact on low end hardware....

They do yes. But they massively improve immersion.