Your title is talking about Bulkinendpt and your question is talking about control endpoint. Please provide more information.
With regards to the limitation, I don't think there is a restriction. I've not really tested with 1024 byte payload but i've tested till 512 byte payload.
I'm using both. Question applies to both I guess...
Is XferData limited to one packet size or will it send a full1024 without having to be called multiple times?
Unless and until and zero length packet or a short packet is sent in the middle you should be able to get 1024 bytes. You just have to take care that you give a long enough timeout value.