Operator Secific vs. Vanilla Handsets

I just had an interesting chat with the sales guys in my local branch of Carphone Warehouse. I was inquiring about the new SonyEricsson (SNE) C902 phone, and so asked them which networks it was available on. They replied that it was supplied in with either O2 or Orange contracts. (Interestingly, the CPW website also mentions T-Mobile, and it should be noted that the company no longer resells Vodafone (VOD)).

Now, I'd recently tried out another phone which had a horribly slow and clunky operator-specific UI on top of the usual slick midrange SonyEricsson menu and app software. So I asked the CPW staff "Which version of the phone [Orange or O2] has the better software?". The reply surprised me "They're the same, we supply the phone with the generic software".

Now the reason for this can't be logistics (ie desire to avoid stocking separate versions of each phone) as I'll bet that each one still has physical modifications like operator logos. So I'm wondering instead if there has been some push-back from customers about operator-specific differences between phones. I've thought for a while that the handset review magazines and sites really ought to compare between operator variants of the same phone. And anecdotally, I'm certainly aware that some UK consumers are certainly aware that devices' capabilities and usability differ.

Obviously in instances where operators have exclusive rights to given handsets - or more-material customisations - such comparisons can't be done. And in markets like the US and Japan, it's quite common for many devices to be very-tightly specified by a single carrier.

But for popular devices like many Nokias (NOK) and S-Es and Samsungs, do the mobile operators really want to compete on whose version of a given device is best? Obviously the quick answer is "Oh no, we'll compete on the services available on our version of the phones". While there may well be specific custom client software (to access custom services), this ignores the more in-your-face changes to top-level menus and UI that some carriers insist upon. It's minor things like populating the home screen with unchangeable links to stuff you don't want, or locking the browser's home page, that customers will be irked by.

There's also another question here - will the generic versions of phones supplied by CPW work well with all of each operator's existing service portfolios?