The main problem with MBHD is that it's fee structure was set quite low. The maximum you could set was only something like 100 sats/byte. This was a VERY big problem when support for MBHD was officially dropped last year as fees were quite high. There was a good chance that you anything you attempted to send directly from MBHD would end up getting stuck.
Currently, fee levels are relatively low... bouncing around 1 sat/byte to 40-50 sats/byte... so you could probably just spend directly from MBHD... however as this mornings little surge proved, it's easy for fees to spike!
Additionally, MBHD can have issues if any transactions are received that use newer "features" (like SegWit etc)... the old version of BitcoinJ that MBHD is running on doesn't handle these transactions well and you can end up with the "Password did not unlock the wallet" issue. Personally, I would follow the instructions in the video (
https://www.youtube.com/watch?v=E-KcY6KUVnY)... restore your wallet into Electrum using the seed and appropriate derivation path and go from there.
After you have succesfully cloned your MBHD wallet in Electrum, you might want to consider creating a "native" Electrum wallet that uses SegWit by default... and then transfer the coins from the cloned MBHD wallet to the native Electrum one.
Summary:
- Clone MBHD wallet in Electrum using "I already have seed" and "BIP39 seed" option
- Create new "Standard" wallet in Electrum (with a new random seed mnemonic) that uses SegWit
- Send coins from cloned MBHD wallet to new SegWit wallet