H&H mining system is superior - much more details and layers plus veins looks much more logical and dont make mines 100% source of infinite high-Q metal - probably just because Salem mining was never actually finished. Hopefully they will take best from both games and stick with developing this last game. While i do like Salem potentian and basics more (and graphics wise of course - this one important as i think it takes A LOT of time to make this for new game, time that can be spent on developing systems we have already), i still feel H&H has more details and polishing in some game systems - be it mining or others. On the other hand farming and cooking in Salem are more complex and intresting then H&H ones (we need cheese ! ) Boards could be intresting but now its more of time-sink.
I would prefer they would stick with Salem development but since bad start it looks impossible to lure many new players ingame - and thats the only thing capable to make mmo alive - it cant be only 300 H&H hardcore veterans. In most mmos hardcore gamers generate most intresting dramas and inspiration for other 90% of players. The reality is those 90% that makes world alive, while being inspired by hardcore gamers deeds, actually cant or dont wish to do same - but still they do need something to dream of.
ps: I wonder what would eve-online look like if CCP would start new game every 2 years... and i do remember eve-online of 2004 and the difference is huge compared to 2014. And usually it was better to read about big dramas/great battles then to actually take place in one due to technical issues or metagaming - still those deeds did a good motivation and provide stuff to talk about for others.