I use a 240gb iPod 7th gen. Mod kit or completed mods are readily available on eBay.
Yes I think to a certain point a good USB LOD is better than a cheap USB LOD. The way i understand it is that data being transmitted in music format which is bit for bit in real time is not the same as digital file transfer, I doubt the former has any error checking at all and is prone to loss whereas the latter has much error checking built into send and receive ends to preven file corruption. Therefore rf interference and other factors do play a role in data transfer in digital audio. But I feel after a certain quality it's less relevant. Happy to be proven wrong though.
Was there anything else I missed in your post? I read all 350 pages of ES5 thread before receiving mine so 40 pages is lightweight!!!!