According to my very trusty little black book, there is no Star Gold lounge in VCE, so the LH lounge would indeed be for their members only or for applicable classes (Intnatl J/F etc). *G access is at "designated" Gold lounges only - and they are in the minority of the total lounges operated by the * carriers.
As for seamless, it can be hit or miss at times, but for the most part it seems to work okay. It would certainly help if they get Starnet working to full potential !!
How long have you been G with BD? If their system is not as yet updated completely, information may not be transferring to the other carriers correctly, or if you went through a third party (agent) they may not have entered the details correctly.
LH and SQ are very much "by the book" which goes someway to explaining LH's attitude on occasions and SQ's consistent profits!
In the end, the alliance you want to be with is the one that satisfies your normal travel requirements the best. Star can do much more for me than any of the others can and offers me far more options for my travel habits.
Cheers.