Re: Dual SIM
"they claim that's dual active which would be ideal. Never had a phone that could do that - does anyone have any experience of how that sort of thing works in practice?"
Very well indeed - I had a HK$260 dual Sim phone (GBP ~22) which I had one DUAL number on the SIM, one a number in the Philippines so that anyone there could send me a ONE PESO SMS = a few UK pence to anywhere in the world that I was..... and it also included a PAYG Hong Kong Local phone number too.
The second part of the dual SIM was filled with another PAYG Hong Kong Local phone number - so I had a choice as to which HK number I used... and effectively - a backup if one of the SIM's credit got exhausted.
A HK$48 Rechargable SIM sell for about 50% of the face value in ShamShuiPo, Kowloon, and I almost always discard the value expired SIM as it costs HK$48 to buy a HK$50 recharge card. The only time I have "recharged" is when I still had a large credit balance left as the SIM was about to "Time-out".
I've no objection to tossing out my old mobile numbers - they are expendable here.
I've NO desire to pay vast sums of cash for connections that I seldom need to use.