From $5+.50 SNG to $20+2

I know it's reasonable to assume that when you move up through the levels in 1 table SNGs, the level of competition is better and therefore your expected ROI will decline. I'm wondering by how much.

For example, say a player has a SNG sample size of 500 games at the $5.50 level with a ROI of 18%-20%. I know 500 games is not the greatest sample size, but I feel it's good enough to see if you are indeed a profitable player +/- a few percentage points to your true ROI.

Given that information, what could a player seeing a ROI of 18-20% at the $5 + .50 level expect at the $10 + 1 or $20 + 2 level?

Is there anyone with an abundance of volume from these levels that has some numbers to share?

I know there are a lot of factors to consider, so feel free to elaborate in details if you wish as I'm fimiliar with all terms associated with SNGs.

I will be honest with you and tell you this, skill level barely even changes so your roi will still be about the same, prolly around 15-18% which is really good.