The pack itself is awesome, as it's a nice, different play style to try running around without Thermal Expansion and other mods that can easily make endgame come up that much faster, but it feels sort of bare at the moment.
I've recently started a pack on 1.2.0 on a private server for some friends, and here are some of the mods I've added without incident, as they really tie some things together:
Chisel 2 (Decorative blocks and little overhead, what's not to love?)
Bibliocraft (Being a witch without bookshelves from this mod is annoying, and it looks nice for Thaumcraft essential phials as well)
Forbidden Magic (Integrates Thaumcraft with every other major magic mod such as Witchery, Blood Magic, and Botania, with a darker twist on most)
Equivalent Exchange 3 (Because why not, and it's magically themed, if not enough to quite stand up on its own. Also adds portable bags... which this pack is otherwise lacking)
I tried adding OpenBlocks, primarily for the purposes of the grave stone portion (since I get tired of refunding them over silly deaths...) and some other useful utilities, but it won't start with OpenBlocks enabled.