You don't need it, I mean if you want to spend heaps on a white elephant go ahead but there's no need for any home usage. Streaming 1080p in any common codec will work over a 100Mb link just fine, so unless you're streaming uncompressed RGB 1080p (that is to say, unless you run a movie studio) there's no need.
So, maybe you want to transfer RIPs of bluray disks really quickly, well sure I guess it might be justification if you've got more money than sense but you'll need 10Gbit, bonding links depends on multiple traffic streams as ether-channel balances on source and destination mac address. So no single transfer will ever go over 1Gbit anyway.
Lastly, if you're getting 70Mbps, something in your current setup is rubbish, you'll get at least 90Mbps even on home gear if your disk system is capable. Jumbo frames likely won't help much, plenty of tests show a reduction in throughput with Jumbo frames but enabled but then again it won't harm either, won't affect quality at all, packet size will have no affect.