Well after a bit of time with V5.3 HF1 my conclusion is that LM's default terrain mapping etc is ok. I could see no significant difference with ORBX Vector in fact in some areas it looked worse (highway size, definition etc). So I no longer use Vector at all. I still use ORBX Global Base and their HD buildings and Trees (These are definitely better, smaller and more system friendly with more variety and accuracy). LM definitely have tidied up P3D to the point where for coastline and terrain accuracy that ORBX Vector is no longer required. Performance is not noticeably improved but I have not had any performance issues on my system anyway so probably not a good guide there.