Hi Justin, couple of things.
Firstly, In the SDK looks like the sizelimit is for List controls in the JSON model, this may not be relevant for the sap.m.Select, I'd like to verify this as fact but my assumption is that setSizeLimit is relevant for sap.m.List controls or controls under that class hierarchy?
Second, why do you want 1000 items in a sap.m.Select, wouldn't this be a poor user experience?
If I had a requirement where there is a 1000 objects in a list, I would go for a search help with live select, kind of like the employee type searches in standard Fiori apps.
If the requirement is to use a sap.m.List type control, we always page the items.
Can you justify the requirement to show 1000 items on a sap.m.Select( long scroll time I'd suspect )?
There are other nicer design decisions to consider for this if you could share your exact business requirement.
Leigh