i gotta admit i play my magic pack on 1.7.10, but mainly because i'm too lazy to upgrade. as a mod user building a new pack to play, i would go for 1.10.2, which already has a lot of mods available (as mentioned, easy update from 1.9) and also some new mods which don't exist on 1.7.10.
the "main" technic mods are all updated to 1.10.2 already, and it seems like the modding community is "setting up there", as someone else said.
only thing that is definitely missing is buidlcraft and therefor a decent quarry/autominer. but the benefits are on 1.10.2's side. and btw, this would also solve your conduit problem.
so... i will start at the top. first of all, we didn't use IDs back in 1.7.10. we had a pretty stable system where the mod author gave an unlocalized name to his item and forge would automatically assign it to a free ID.
with 1.8, severe changes were being made, so updating "easily" (copy-paste and correct some import paths) wasn't possible any more. as a consequence, many of the more complicated mods took a long time to update or didn't update at all, since their owners didn't have the time for such a huge update. some mods even needed a complete rewrite. 1.7.10 remained a big mark for the modding community, since most older mods and therefor a lot of modpacks were running it. think of it like a reservoir, the majority of mod got stuck there for some time (or forever) due to the dam.
now it seems like the modded community is setting up at the 1.10 versions, on the one hand because it's a simple update from 1.9 (in fact, most 1.9 mods run on 1.10 without any update at all), on the other hand because 1.11 took some time to come out after everyone updated to 1.10.
i as a modder would recommend to either stick to 1.7.10 (great for nostalgic players), or, my preferation, to directly develop on 1.10. if 1.11 and the follow up versions provide an easy update again (similiar to 1.9 -> 1.10), then you won't have problems going with the stream, if bigger changes to the codes will be made, you will have this reservoir-effect again. to conclude it, if you develop on the latest versions, you're on the safe spot.