GT5 is for 1.7, and GT5U (an approved but unofficial fork that added in a bunch of the end game stuff from earlier GT that didn't get into GT5, such as 3 tiers of fusion reactors) is used in at least a couple of modpacks (including Infitech 2, a 3rd-party pack on the FTB launcher.)AFAIK it is not a good time to try GT for the first time atm. It is in a very unfinished state(WIP) for 1.7. It is what is keeping TPPI2 in (perpetual) beta for example.
I personally couldn't live without GraviSuite, so IC2 is a must no matter how much I want to use it or not. Not sure about its 1.7 state, but I am also generally fond of Electro-Magic tools that bridges IC2 and TC and think I will be adding that in the future as well.
Bees are just a fun hobby for me. I don't actually use them much for all the infinite resources. Only for the ones that are not available through other means(mostly bee or forestry stuff). But I generally just love the process of it all So also a must.