perhaps this may help others - it's the way i'm playing it.
I have a touch diamond original and will be buying iP4 soon after release - will be my first iP. I had Simplicity 30d for smartphone @ £25pm: 600m, Unlimited texts, Unlimited data (Ud is a £5 bolt-on, otherwise £20)
11/6/10 - 13:30: I changed to Simplicity for iPhone, 30d - 900m, Ut, U Wifi, visual voicemail and Ud - AGREED ONLY ON THE PREMISE I WOULD KEEP PERMANENT UNLIMITED DATA DESPITE CHANGING TARIFF. I WAS 100% ASSURED BY LADY THIS WOULD BE THE CASE AND I WOULD NOT BE AFFECTED BY UPCOMING DATA CAPS POST 24/6, as long as i do not cancel my contract or change to non-simplicity tariffs.
Today (13/6/10) - 09:07 - Was told that on 21/6/10 my new tariff will take effect. she checked with upgrades for confirmation re: Unlimited data and was told that that only applies to people who will get 'iP4 contracts' so i will always have Unlimited data.
To be on the safe side I told her to put a note on the system stating that I had selected and changed my tariff to iP Simplicity 30d on the assured understanding that i would always have Ud unless i decide to change my tariff or end contract in the future. She agreed to do so.
The way I look at it if it turns-out staff are morons and don't know what they are talking about, and my data gets capped, i can really lay into them and hopefully get them to leave my data as it is due to their employee's ineptitude. worst case, i'm only on a 30d contract so can easily jump ship. i guess for those who are trying to get onto new Simplicity tariffs as opposed to changing from one Simplicity to another, things may be different...
major selling point of iPhone for me is being able to upload those high-quality images to flickr etc. and half-decent looking iMovie for iP4-edited vids directly to You-Tube etc. i wish they would give option to upload them to Vimeo...