I find that people who own product based businesses do well with 1ShoppingCart. If you are offering products you'd like to sell right from your website, this is a great option. However, there are some things to be aware of, it isn't as easy to sell directly to segmented lists. You'll have to manually segment the lists rather than having more intuitive options. There are other things about 1SC that I really like and definitely see its benefits for sure. Many people I know who use this service are highly product based and its important that they have a reliable cart that works easily and without problems.
I don't see 1ShoppingCart as the best option for someone who owns a coaching or consulting business. There may be too many options and since these businesses are based on the list, I'd recommend another service to get more for your unique situation. It's important to look at what you are looking for in your service - are you looking for streamlined marketing avenues and integrated cart with customer service options? Then 1SC may not be the best option.