You're definitely right in saying that the escrow market seems pretty much saturated at this stage with many of the big players offering 0% fees. I did a lot of reading on Bitcoin security over the past year and I feel I have good security practices in place but if the 0.8% fee turns out to be too much then I might relaunch the service at a later time with no fee and tips instead.
EDIT: Also one advantage is that I might be able to offer escrow for IPOs/ICOs for a 0.8% fee although this would depend on the complexity of the IPO/ICO (e.g. simple NXT-style IPOs should be no problem).