New member question re: Batman movements

Hi RGs. I just joined your site and look forward to continuing my education on your interesting forum. I have a small Rolex collection which is a mixture of Gens and Reps. In the past I purchased a few reps on DHGate with predictably mixed results, mostly poor. Now I am looking for a new version Batman and perusing the TDs. TD InTime, which seems to be well liked, has a BLNR with new jubilee bracelet and 904L steel in both the case and band. It has a 2836 movement for $438 which seems reasonable to me. But another TD, Hontwatch, has what sounds like the same spec'd watch except with a 3186 movement and the correct stack for only $20 more, $458. My question is, is the 3186 a better movement than the 2836, and if so, can I expect as nice a watch from either TD? As an aside question, both TDs have the BLNR 2836 movement but in a case/band of 316 steel instead of 904L, for $278-308. Is 904L steel worth $140-160 more? Thanks for your opinions. HH