I don't know what you are trying to achieve besides having both groups of friends playing together. For which this kind of works.
Tekkit comes with modular power suits mod though, that will make Battletowers and Better Dungeons maybe a little too easy. Maybe at least set the server difficulty on High ( if you didn't do that yet). Also make sure the Infernal Mobs ability that attacks gear durability is turned off (if you decide to keep power armour). Because it will also destroy power armour. I would remove Modular Power Suits. Because it basically renders Hexxit armour sets mostly useless. And most of enchanting too. Oh and Chocobo's for transport. But that maybe doesn't sit nice with the Tekkit players. IC2's armour is also a problem icm Hexxit.
We used Hexxit as basis and expanded on that theme. I added Thaumcraft (with Thaumic Tinkerer), Mo' Creatures (disabled certain similar mobs in Project Zulu), Carpenter Blocks, Booze Mod, Chisel, Pam's Growthcraft, and some some aesthetic stuff that was requested and which I think didn't interfere (too much) with the Hexxit theme. I also added Railcraft for some automation. It fits better in a lowtech theme and I thought it was a nice idea because in tech modpacks I see it rarely used because of the gazillion types of pipes.
We had a mix of tech with Hexxit before and that is when I noticed the problem of having Modular Power suits in Hexxit. The moment players got that (which is quite early on), the loot in dungeons became mostly useless. Durability loss on armour is important for Hexxit imo.