One final thought: Will you need to be doing a lot of cross-product analysis, or will they mostly be Line Of Business or Product Type specific?
I'm not 100% sure what you mean by cross-product analysis.
Reporting is varied. Some reports will show all Services grouped by category (i.e. there are multiple Service codes that fall under the "Tire Balances" category), another report will show Service categories as well as Product categories divided by the number of tires sold. ("Tires" would be a Product).
Hope this clarifies. I find the unknowns of what reporting will be requested to be the most challenging part of designing.