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It just seems like this aesthetic including placement AND color combination has been done and over-done far too many times (Google, M$ Windows, etc). Maybe try experimenting with symbols for synonyms of "plus" like greater, additional, etc.
The font is excellent.

Tnx Michael, I'll keep in mind what you pointed out and play around to improve it. In fact, I've already made some changes on the concept. You can view the updated version here. If you have any comment on the newest one, I'd be happy to hear.