As a hobbist, I have made several silicone rubber moulds but never used epoxy resin in the construction of the finished product only polyester resin for some end products but no removal issues i normally use a releasing agent even when some manufacturers suggest not needed. Also when making Polyurethane end products still no adhesion issues when seperating from the silicone rubber mould.
Apparently the silicone has a particular oily finished surface after correct mixing (essential) and curing time and this acts as a release agent. however if the mixing isn't correctly weighed and mixed you will have curing and sticking issues, but as with anything the only advice I'd suggest is practice on a few odd shaped objects before your actual project.
I have never had an issue with silicone rubber adhering to anything ha ha and even after an accident and dropped the liquidified solution of rubber I just wait for the required curing time and literally pull the rubber off any surface. depending on the product used and manufacturers specs approx 15 hrs but again depends on product thickness.
When creating timber plugs, I have also used MACWAX and HONNEYWAX for some of the more porous timber surfaces as a release agent, as some of the more porous surfaces can cause adhesion of the silicone rubber.
A suggestion for info is MB Fibreglass supplies online UK & Ireland - mbfg.co.uk, I have not connection to the company ha but for me in Ireland they're on my side of the Atlantic, I have purchased a lot of stuff from them in the past and used them for information only too, by accessing their free MSDS in pdf, ha don't expect an immediate response to an email question but an online order/purchase is delivered promtly.
Additionally a youtube search of Silicone Rubber Moulds or DIY Silicone Rubber Moulding will reveal some interesting videos and facts as a picture will express a thousand words...!
One last bit of advice the curing of epoxy as with some of the polyesters creates heat through the exothermic reaction while curing and this heat can and WILL distort the shape of the curing casting depending on its thickness respectively will increase the heat, this can be resolved by either cooling the mould prior to the poring of the epoxy but not fast cooling when the casting is in the rubber mould ie submersion in water as cooling too fast will alter the mechanical properties of the epoxy casting causing a brittle or fractured product. What I have done to overcome this with very good results is to form my silicone moulds in a box, cylinder or casing to reduce the expansion/distortion from exothermic heat.
Good luck with your project.