Personally I love to see someone downloading a shit load of stuff from me. Someone recently got a whole labels releases from me of over 30gb but that just tells me they have good taste in music as far as I'm concerned so I then explored their files and ended up getting a lot of interesting stuff in return.
I think these people with all their locked files asking for shit like gift vouchers in return for the privaledge of downloading a file from them are scummy, so the way you've approached it sounds great to me, you are sharing so grab whatever you need from people. Hopefully they will then explore your files and the cycle repeats!
Within my chosen genre locked files tend to always mean they want something like that in return. Anyone I come across like this I block out of spite, I love sharing files with people but these people don't deserve it IMO.