Tokyo and iOS 4.0

Today has got to be the furthest I have travelled and returned home within one day…  I got up at 6am to get the train to the airport, flew to to Tokyo and got the train into town, then in the evening was back at the airport flying back and getting home to Sapporo just now at 11pm!  ”What did you forget?” you might ask…   But forgetfulness wasn’t the reason for the trip.  The whole event was a highly organised and coordinated trip to go to the British Embassy (they only have an embassy in Tokyo and consulate in Osaka) to apply to get a CNI (Certificate of No Impediment) which will let Emily and I apply to get married here in Japan.  According to the website I had to attend an “Interview” at the embassy, which I had to apply for (an application so I could apply to get the document I need to apply to get married…), but the whole ordeal took a matter of minutes, with the short walk down the hallway to the next room to pay the fees I was in and out of the embassy in around 30 minutes!  All that travelling for 30 minutes!!

But hopefully it will be worth it!  I took stamps for them so they could send me the certificate in the post rather than going back again to get it, and I got a form that I need to fill in and post back to pay for the actual certificate as I won’t be there to pay for it on the day of issue.  Strangely they wouldn’t let me pay for it while I was there and had the cash, but rather I have to send it.  We had a brief discussion about how I could just go outside and fill in the forms and post them in  that very day which would only take a day or two off the actual time the embassy was responsible for my money…  So I will maybe wait a little while before sending the form in, until that point I was quite impressed by the efficiency of the embassy, but not being able to pay in advance was a sharp jerk back to the reality that the small patch of land I was on was technically British (is it?) and I wasn’t not eager to please and super efficient Japan for that half an hour!  Hopefully it will process and work and I won’t have to rush back to Tokyo with a few days to spare before we actually get married…

Anyway!  A few days ago I upgraded my (already ageing) iPhone 3G to iOS 4.0 and it was lovely for a little while.  But today’s trip to Tokyo tested it to the limit.  I was listening to music and catching up with podcasts (and Bill’s latest messages from First!) while finding my way with maps and GPS, looking up train times online, writing texts and an email or two, tweeting the odd tweet and even watching a YouTube video or two at some points of non-activity.  This was normally not an issue, it could do all of these things fine, and probably still can as long as two don’t happen at once!  But after a short time using it, it started to be unbearable.  It was very slow responding to key presses, particularly on Japanese input, it ground to a halt more than a few times apps were crashing left right and centre and even once it needed an all out reboot!

So long story (slightly) short: I want to go back!!
But it isn’t easy.  From looking around it seems that I will basically have to go through the “jailbreak” process to install the older version 3.1.3 of the operating system…  So my question is, should I just jailbreak it?  My reasons for not doing it before were that it just seemed like too much hassle, and the little risk involved was probably not worth any of the benefits…
But if I am going to have to do it anyway to get back to functionality maybe I should just do it?  Has anyone out there jailbroken their iPhone 3G and have any experience?  Good experiences?  Bad experiences?  What are the risks and what are the main benefits?  Would Softbank go nuts on me?  If I went to the apple store (urgh) would they restore me back to 3.1.3 or tell me I should be glad to have 4.0?