I own both a M14s and a mini 30 and have a shot the mini 14's quite a bit.
I prefer my m14s.
The m14s are easy to work on, but there can be a shortage of parts at times to work on them.
recently with LRB starting to come in we should see the price drop and the availability increase.
in terms of customizing ans tuning the mini 14/30 there is not much. compared to the m14s/m305, direct from the factory things are good to go, where as the m305s, to get a little more accuracy, sometimes require gas block shims, guide rods etc.
Triggers on both/3 are not great from the factory. this is due to the design, however a competent gunsmith should be able to tune them.
as for recoil. the m305 is very pleasurable to shoot due to the semi auto-ness.
my shoulder has no trouble after a lot of rounds.
bullet selection on all three is alright, if you intend to hunt (in alberta at least) the .223 isn't legal and the mini 30 rounds are going to be around 20 a box.
mounting optics on all three is easy, but not cheap. the factory ruger rings, IMHO are crap. I dislike the design and the screw need locktite to hang on.
all three are hard on optics due to, again the design. Do NOT cheap out. buy something that can handle the abuse.
plenty of good threads in the MBR section about mounting scopes on the m305s.
that's all for now, might add more later...