BW- BPS and SEM- BPS

we are in proj prep phase and have to make a call which one should we go for BW- BPS or SEM- BPS. Actually, we are implementing Budgeting, planning and Forecasting and have to do allocations (little part).

I heard we have do not have allocation functions in BW-BPS. But what other advantaged we have with SEM BPS over BW- BPS or vice versa.

What other factors should we consider inorder to make a call.

Could you please through in any Ideas and suggestions or point me to relevant documents you have on these.

Thanks

Sridhar