I've been using these decoders with 16' 5050SMB led tape and these power supplies on several shows with no problems now. http://smile.amazon.com/gp/product/B00ONQ4BJ8?psc=1&redirect=true&ref_=oh_aui_detailpage_o08_s00
I used these: http://smile.amazon.com/gp/product/B00ONQ4BJ8?psc=1&redirect=true&ref_=oh_aui_detailpage_o08_s00
with a bunch of 5050smb led tape with DMX decoders and have had no problems at all. Used on several shows this year. I just cut the connector off and used the wires right into the DMX decoders.
16' is no problem. There's a definite drop if you add a second tape in, both in overall intensity and by the time you get to the end of the 32', the end is dimmer than the beginning. With 16' (one tape) there were no problems.
If you have more problems, let me know. I've done a whole bunch of 5050SMB stuff this season.