I already asked here about your backend security
https://bitcointalk.org/index.php?topic=5227411 and people are still optimistic about closed source solutions
But i will ask once again anyway. Are you planning to make your wallet open source or at least do an audit?
Open source is not guaranteed to you anything. Are you going to check any release? Is anybody going to check any release of not so popular software? How you can prove that this code is really used to compile the program? Thats questions destroy the sense of open source. IT world is a world of trust. You always can use a paper wallet instead
The point of open source is that anyone can check the code. I don't want to be an asshole but it's strange to hear so many doubts about open source from people, half of whom are more likely to be consumers (i.e. interested in crypto), not the specialists. AND they rely on third party opinion about this code.