I have Drift Ghost-S cameras. The Stealths are smaller and slightly less capable, but more than adequate for bike use.
Build quality very good. Easy to operate.
Pretty happy with my Drift Ghost HD, bought secondhand for ?100 with a box of bits and a mic. S version is considerably better in low light though, so bear that in mind going into winter.
Olfi might be what pure looking for
Similar spec to the GoPro Hero 4 Black but with a longer battery life + image stabilisation. Has 4K capabilities but certain settings are slightly restrictive in comparison to the market leader
They've replaced the model I bought but ?115 pre launch I couldn't say no - even bought my dad one!