Hello,
I'm not sure if you had your question answered. However, I would ask some of the following to get a better understanding of your customer's needs for a planning and budgeting system.
1) What level of detail do you budget (i.e. how many chartfields/dimensions)?
2) How many accounts do you use for budgeting? Best practice is the 80/20 rule..80 percent of the detail is in 20% of the accounts.
3) How many users are involved in the budget process?
4) Do you currently use scorecards/kpi's? This will be key to having some sort of measurable metrics once the implementation is done.
5) Do you currently utilize spreadsheets?
6) How many iterations are there of the planning cycle?
7) How many users utilize the system? Describe the various roles and responsibilities.

Do you create multi-year plans (top-down) that act as targets for your budget (bottom-up)?
9) Does your budget feed into your forecast?
10) Do you using rolling forecasts?
11) What primary budgeting activies are utilized (revenue planning, expesnse planning, etc.)
12) What types of methods/formulas do you use to create plans?
13) Do users have the ability to create formulas at anytime during the budget/planning process?
Hopefully this helps.
Corey