My 2 cents:
Using Electrum, or Hive-web/Hive-iOS is a good idea. Hive for OSX (Mac computer) is not ideal.
Reason:
Because Electrum and Hive-web/Hive-iOS use what is known as "Deterministic" wallet structures.
What is a "deterministic" wallet, and how does it differ from a normal (ex. Bitcoin Core / Hive-OSX) wallet?
1. A normal wallet must be backed up frequently. Whether this is once a month or once a year or once a day depends on how much you use it, and it is also not intuitive as to when you are using new addresses that were not in a previous backup. (Especially Bitcoin Core, because they actually create hundreds of addresses in the background and hide them from the user with no notification as to how many you have used.) Because of this, people who are (rightfully) paranoid tend to backup their wallet.dat file frequently, and then remembering which backup has which password etc. can become confusing and lead to loss of access to the user's bitcoins.
2. In comparison, Deterministic Wallets only need to be "backed up" once. This is because the 12 word phrase that is given to the user upon creation of the wallet IS the wallet itself, and all new addresses are generated FROM that information in an indexable way. (ie. if I take the 12 word phrase, then pick a number like 56. Every time I put those two pieces of information into the wallet software it will ALWAYS generate the same address.) Because of this. Deterministic wallets usually let the user use the most recent, non-used address in the "chain" of addresses. Because of this, if you take the 12 word "seed" and use it in wallet software to restore your bitcoins, it just keeps checking each address from 1 to infinity until a certain number of unused addresses appear, then the wallet assumes "ok, this person didn't use addresses 78 - 88, so we'll assume his wallet only contains addresses 1-77." etc.
3. Also, another interesting feature of Deterministic wallets is the fact that this "chain of addresses" can be generated WITHOUT the private keys AT ALL. This allows you to set up an online computer that only watches balances and manages transactions. Then create a separate, offline computer / boot device that contains the PRIVATE keys (to spend your bitcoin). A normal wallet can not do this, as normal wallets REQUIRE the private key in order to generate the addresses. Explaining why/how this works is very difficult... so unless you want me to bore you with Elliptic Curve math, just know that it is possible.
However, there is one drawback of deterministic wallets, and I explained it in the thread on the Electrum subforum.
4. Using "Export Private Key" on Electrum is dangerous. So if you need to use some sort of service that requires importing private keys. It is recommended to send bitcoins to a separately generated address (like from bitaddress.org) and then use THAT private key. The reason why is complicated. (You said you couldn't understand on the thread) But in short, a person who knows ANY ONE of the private keys generated from your Electrum wallet AND the "MPK" (Master Public Key) from the same Electrum wallet can then generate ALL of the private keys from your Electrum wallet. So it is considered to be a BAD IDEA to export private keys from a deterministic wallet, but SOME services for bitcoin require/allow importing private keys. This can confuse the user and lead to stolen coins.
HOWEVER. As long as you treat every private key in your Electrum wallet as if it were a "Master Private Key." You will be fine.
Hive-web/Hive-iOS understood this and 1. Does not allow exporting of the Master Public Key. and 2. Does not allow exporting of any private keys. (However #1 prevents people from doing an offline cold storage wallet solution)
tl;dr
If you are holding a large amount of bitcoins. I would suggest reading any number of "sending from cold storage with Electrum" guides and using Electrum. PLEASE WRITE DOWN THE 12 WORD SEED ON A PIECE OF PAPER, AND TRIPLE CHECK THE SPELLING AND ORDER OF ALL 12 WORDS BEFORE STORING THE PAPER IN A SAFE PLACE. (ie a safe or something) Many people "forget" to write it down, or "was meaning to get around to writing it down, but then my computer crashed" and they lose bitcoins. AS LONG AS YOU HAVE THOSE 12 WORDS, YOU HAVE YOUR BITCOINS.
If you are using small amounts for spending, and you have an iPhone. I would suggest using Hive wallet for iPhone and
https://web.hivewallet.com/ with your computer. These two can accept the same 12 word phrase and use the same wallet on your phone as your computer.
Keep in mind, though, that Electrum 12 word seeds and Hive / Breadwallet / Wallet32 / other deterministic wallets are NOT compatible. So as a general rule of thumb, use the same 12 word seed with the same service to recover your bitcoins. Using the 12 word seed from ONE service on a different service may not restore your bitcoins correctly.
