For anyone interested...
I've been using the Tune Belt IP5 belt for over a week now. It's mostly been a positive experience and for anyone debating whether to get a waist band instead of an arm band, I can recommend it. It's very comfortable to wear. The 1020 fits well and snug and doesn't bounce around..it is kinda hard to notice wearing it when running.
Getting the phone in is a breeze but getting it out again can be a little fiddly. I'm not sure if this is because I have a screen protector on the 1020 which could be adding extra grip against the clear window of the belt but I have to force a couple of fingers in between the phone and belt window in order to pull the phone out. Also, I'm not 100% sure it's waterproof. There are clear gaps at the velcro end where I plug headphones in. I usually wear my SBH52 headset when out running so this isn't usually an issue but on the couple of occasions when it has been raining, I haven't wanted to take the chance getting the headset wet so have taken my Sennheiser in-ear headphones instead. Common sense suggests to wear the belt under a running shirt so it's not only more discreet but provides a little extra protection from the elements, but I'm not sure I could trust it to keep my phone perfectly dry in a heavy downpour.
All in all, pretty good piece of kit. Very comfortable and does the job but slight reservations about using it in heavy rain.