In my personal opinion for my own requirements (cashflo's disclaimer here) I wonder if Bullion Vault hasn't bypassed the whole issue about owning gold and just come up with an ingenious alternative which is not fundamentally the same. It would be interesting to see the legal perspective of the defination of "ownership" should you rush in and buy 2 kilos - you've only agreed to their terms and conditions an literally all there is in reality is a computer entry or piece of paper with your name account number and the quantity of the yellow stuff beside it - not that much comfort if the dow's just lost 600 points and a there's rumors of a hedge fund collapsing!
The ebay aspect now makes a whole new aspect to the private sale of coins. The most popular on there seem to be 1oz Krugerands and whereas before the only places you could sell to in quantity would be dealers you can now sell at roughly the markets buy price. My worry previously was thinking at some point in the future when gold is £1000 an ounce, great I've got x amount of Krugerrands but the dealer is only offering £880 per ounce with some elaborate excuse - but charging £1100 to buy the stuff!
(I'm not joking about that spread either)
Also some of my other thoughts were, I exepct general public participation in gold investment to incease ten fold in the next few years and for ease of sale a half or quarter ounce krugerrand may be more apealing to the individual - (if gold rises accordingly) alot of people may simply be put off paying £400+ for a coin but £100 for 1/4oz coin seems more reasonable - just my take on the the publics perception of price. Ultimately it probably won't make that much diference.