Star Gold is enough yes! And with LH you can use the first class checkin at FRA/MUC when travelling in Y what more can you expect Star Alliance carriers to give you?
To be honest some F lounges are good, and some are not much better than a LH Senator Lounge or a Silver Kris C lounge (eg LX ZRH First Class -a major disappointment and recently spent half my time in the Senator Lounge Half time in the F lounge - at least I can smoke in the ZRK C lounge bar - with no smoking in the F lounge )
Compare the LH arrivals lounge at FRA with the LX Arrivals lounge at ZRH - major difference and neither is available to Star Gold unless you happen to be a Miels and More Star Gold
The extra baggage allowance is a major benefit and at least it is recognized throughout the alliance without any hassles (unless you get the Athens ground staff giving you problems when flying A3 Y)