I am kinda 50/50 on using Heatran LV. X. Should I use LV.x's for my deck?
YES. Level X cards are just like EX cards, but from previous packs like DP Promo. They are realy strong, powerful, and very threatening. DEFINATLY, yes.
It is mostly a matter of opinion, as you said. It all depends on if you have a good deck that can support the lv. X or not. If so, it is worth using, but setting up a level x is hard as it needs a lot of energy to get where it needs to be.