Is Nexus S still a viable upgrade?

Hello, fellow Android warriors! ;)

I am thinking of getting myself an early Xmas gift and upgrade my phone.
Currently I'm rocking Orange San Francisco, a branded variant of ZTE Blade, running CM7.1. It's a cool budget device with a gorgeous WVGA AMOLED, almost unbeatable in 'bang for a buck' category. The phone does most things I require of it well enough. But the old chipset (ARM v6 MSM7227, clocked at 600MHz) doesn't feel snappy and battery life isn't stellar either, not getting me through the day with data on (worse when overclocked)... I'd also happily enjoy bigger screen - Blade's 3.5-incher has great colors and pixel density, but it is quite small.

If money was no concern, I'd of course preorder Galaxy Nexus and call it a day. But then, I probably wouldn't have bought a budget device in a first place, right? So my budget *is* limited, to around 400 USD/ 300 EUR. Phone unlocked, unsubsidized, available in Europe or at least working with European GSM and UMTS bands (900/2100).

My first idea was: "I can't afford Galaxy Nexus, let's get Nexus S and also get a taste of that yummy Ice Cream Sandwich!". But then came the afterthought - Nexus S is one or even two generations behind the curve, with single-core CPU etc.

Here comes my question - do you see Nexus S as a viable upgrade at this point? Or should I look in the direction of cheaper dual-core devices, like LG Optimus 2X, wait a bit for ICS update rollouts? Maybe get a slightly cheaper, basic Galaxy S?
Maybe I shouldn't upgrade at all, as the current device is capable enough for my basic needs?
(I can easily think of at least 3 different purposes for the money - new 23" display for my PC, SSD for my laptop, a cool holiday trip with my GF ;))

Looking forward to read your insights, may they be helpful :)