My experience of stainless bolts is not quite the same as that of JohnChapman, but similar.
Stainless bolts can gall, and that is a real PITA. Ways to avoid it are to use different stainless grades together (303/304 bolt, 316 nut) and/or to use something like 'Duralac' which acts as a lubricant to stop galling & prevent corrosion. The company I work for uses around 20,000 A2 stainless nuts & bolts a week. Failures due to galling occur once or twice a year with those precautions. Blind holes should always be gummed up with Loctite/duralac because stainless steel is only stainless when in the presence of air – the chromium oxide is in a dynamic equilibrium with the oxygen in the surroundings, and if there is no oxygen in the local area, the oxygen is lost from the chromium oxide, and not replaced, leading to a thinner/less complete oxide layer, so corrosion is able to start. If in a blind hole, it can get wet & then there is little air, so corrosion accelerates. To stop it in a blind hole, you need the duralac/Loctite to exclude water in the same way as for a standard steel bolt.
As for strength, agreed. General A2/A4 bolts are grade 70, ie 12% weaker than a grade 8.8 bolt, and they yield at 2/3 the load. Cap head bolts are nearly twice as strong. If you are machining 303 stainless, you won't be certain of the work hardening level (unless stated on a certificate when purchased) & need to assume it's annealed. In the annealed state, they won't be much stronger than normal DIY store studding. Not a good thing!
Regards,
Richard