HL are as good as ... if not better ... than any other manager.
Operators like those of this fund WILL get raided if the regulatory authorities believe they have criminal funds invested in their fund.
There is a chance no matter how remote that access to...and heaven forbid real loss to you may result.
Also fund managers charge fees so you ARE paying twice....Once the mangers fees whatever they are AND the mining transaction fee each time they transact on their investors behalf.
A bit coin wallet on any device is secure there as ON any other device.
Your security is as good as your ability to keep your PRIVATE KEY.

If your iPad dies for ever you can recreate your wallet on another device and reaccess your bitcoin.

The bitcoin are NOT in your wallet.
The Bitcoin are in the blockchain transactions. Forever secure.
Your wallet holds the keys to access your unspent bitcoin.

Do not be afraid of your hardware dying.

It is all crypotographic and safe.
DO NOT LOSE OR LET ANYONE GET YOUR PRIVATE KEY.... They can access your money.
Just as HL can access your investment.

What you have done is add a trust element to your savings that bitcoin eliminated.

Good luck!