The price of GH/s is too high now.
Maybe if you have 4-5 or 10 BTC, then yes, will have a good profit if you invest, but with small amounts of 1 BTC or even less is pointless to invest.
Not sure how you arrive at that conclusion. If it's a bad investment for <1
BTC, it's a bad investment for 5
BTC or 10
BTC.
It never ceases to amaze me how utterly incapable the people on this forum are of doing simple math. I'd blame it on the U.S. public education system, but many of these people aren't from the US.

To be fair though it is true that most manufacturers will sell their larger miners at lower cost per GH. However this increase in cost-efficacy is usually marginal. In this particular instance I don't know of any mining purchase for 5 or 10 BTC that would net you much better price per GH than a 1 BTC purchase.