I got this card two years ago with a 2K SL. I have put quite a bit through it and it has been stalled out at 6K for about a year now. I think when you get one of their lower tier products it is much harder to get the limit increased to anything useable. My other business cards that I use regularly have much higher limits and don't report to my personal reports.
I think after about 1 in business you can get a regular Spark. We started with a regular but have many years of business and a good Dunn & Bradstreet file. The minium for regular used to be around $2000.