As a non-techy type of person with limited ability, I'm not sure if I understand ThomasV's undoubtedly good, solid, expert advice. Terms like 'RBF' and 'binaries' just lose me, let alone fiddling about with code, although I'm reasonably sure that essentially such things are easy to understand by the experienced. To help get my mind around the problem of coin-splitting and countering the replay attack would this work:

Using two computers (A with original the wallet and B with a freshly installed wallet), both running on Windows, copy the [Electrum] folder located in the [Roaming] folder on Computer A to the [Roaming] folder of Computer B, overwriting the the fresh wallet's Electrum folder with the original wallet's Electrum folder.

• On Computer A, open the Electrum wallet and turn off automatic-connect and manually select a server running Core BTC. Would this effectively make the Electrum A wallet a Core BTC wallet?
• On Computer B, open the Electrum wallet and turn off automatic-connect and manually select a server running Unlimited BTU. Would this effectively make the Electrum B wallet an Unlimited BTU wallet?

Well, would this be enough to split the two coins?  But what about Replay attacks - how could they be prevented in this scenario if this approach is feasible?

Or, should I just simply send my BTC to an exchange shortly after a hard fork and let the exchange do the coin splitting etc. for me?