the halogenated (Cl, Br, I) members of the 2c-family seem to be very well tolerated by most people, even in 'heroic' or 'stupid' doses like 100+mg of 2C-I.
there have been deaths from 2C-T-7 (see erowid) but these are isolated cases of people combining them with street ecstasy pills and snorting high (30+mg) doses of 2C-T-7. it has been speculated that T-7 (and possibly T-2) due to their sulfur atom may act as an inhibitor of MAO, which can be very dangerous in combination with monoamine releasers like MDMA.
as far as clinical research studies on the safety of these drugs, I don't know of any. 2C-B in particular has had tons of street testing thanks to its high popularity during the 90s.
as always, trip drugs can cause an increase in body temperature. combined with nausea, most people neglect to eat or drink during a trip. it is highly recommended that you keep hydrated during a trip, preferably with salty snacks as well.