What are the physical advantages of riding a single speed with higher chainrings?
The efficiency of chain transmission decreases if one of the cogs has very low tooth count. Track cyclists often use high gear ratios, and large chainrings are used so that a reasonable sized cog can be used. Another reason is that when the cogs are larger, changing to one tooth larger or smaller cog changes gear ratio a smaller amount than with smaller cogs, so larger cogs allow finer tuning of the gear ratio. Both benefits are small, but in racing you use all advantages you can get.

For street singlespeed, the main reason to use large chainwheel is to make the bike look like track bike (isn't this why you bought the Omniums to begin with?). The other popular choice is 42t, because that comes standard with old road cranks and produces nice gear ratio for street use in combination with track cog.