This can have effects elsewhere, however. If you create a custom one to many relationship from another entity to the Quote Product or Order Product entity, then only one of the associated views is used within the parent entity. This can cause a problem, because neither associated view displays all the data (one displays the write-in products only, and the other displays the existing products only). For example, the default associated view is the Existing Products view, so write-in products would not be displayed.
There are 2 possible solutions to this. One is to change which is the default view, the other is to change the filtering within one of the views. Both of these are configured via attributes of the savedquery entity. These can be modified in a supported way by using the CrmService.Update method for the savedquery entity, or in an unsupported way by modifying field values directly in the savedquerybase SQL table.
Which associated view is displayed is controlled by the IsDefault attribute - if you change this then it's your responsibility to ensure only one view has this set to true.
The filtering is applied based on the ColumnSetXml attribute, which is essentially a FetchXml expression. For example, the ColumnSetXml for the Existing Product view is:
<condition column="isproductoverridden" value="0" operator="eq" />
If you wanted this view to include all Quote Products, then you could remove the whole filter and condition elements. Note that such a change would necessarily affect the Existing Product view within the Quote entity.