Probably not, as long as you have put them in various classes. We lump almost all Type R and Type A parts into a raw materials class. We have various classes for Type N (expenses) and Type F (income) items to track expense and income by category. If you are taking the time to put each Type R item into a class that has both expense and income GLs set to toss the debits and credits into the right buckets it does not matter which of the two types you set.

The Forecast field on IN-A was added at the request of a customer who we were doing some other customization for.  For the next update, we will make it include all part types because as you point out, you may have R parts that are bought and resold.  To clarify how this will work, IN-A will first look to see if the part being loaded on the screen has any forecast (as entered in MR-A) and if so, add up if there are multiple records for a total forecasted quantity.  It will also look one level up into BOM parents it goes into and if any of those have a forecast, it will also include them.  We will not traverse the BOM more than one level because we feel it would slow IN-A down too much.  If you have deeper BOMs and a need to see the impact of forecast on demand you will have to look at the reports in MRP.

Yes, that seems like a good balance.