In the SDK there is a sample app called long_characterisitic which is able to send longer packets. I've never personally tested it out. It will only work as a permanent solution if the receiving hardware supports long characteristics which is supposed to become part of the BLE spec.
BLE was never meant to achieve great speed in it's transmission. The most reliable and tested way to send your data will be to abide by the 20 byte limit.
Yes, you'll be able to put 10 16 bit packets into one tx.
I can have a look into this example.
ok so I have to send 250 packets, what's the fastest I can send this?
I am sending these size packets every minute or so for half anhour.. Per use which might be once a week.
its not a very demanding process!