Re: Is there a way for me to use a Mycelium HD wallet in Electrum or vise versa?
Were the addresses shown in Mycelium HD the same ones as were shown in Electrum? I thought they would be different because one wallet uses compressed keys and the other uses uncompressed keys.
This is what I wanted to know as well... as others have indicated that even though you can get Electrum to accept the Seed words from Mycelium, because of the whole compressed/uncompressed keys thing... The result being that Electrum ends up "generating" different keys/addresses from the same seed? 
However, I decided to just give it a go... downloaded Electrum onto the PC and used my Mycelium seed words (along with BIP39 seed option)...
The result: It has (re)created my wallet succesfully... all address (used and unused) match up... and it has even retrieved all the transactions!
Did you only have one account in your mycelium wallet, or did you have more than one? This post by torusJKL suggests electrum might only support addresses in the first account mycelium generates.
Electrum only supports the first/default wallet/account of the in BIP32 described HD wallets.
See here: https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki