I expect it's too soon to make definitive claims about the Dell U2410 v the HP ZR24w. The HP is being released at a lower price point, but Dell may move to bring the U2410 much closer (they've already offered coupons below $450). The panel tinting / uniformity issues are caused by LG.Display's crappy production runs, and I wouldn't be surprised if we find uneven ZR24ws as more punters report their results.
Though the publicity lists the ZR24w panel as 'S-IPS', tech specs cite an 'H2-IPS' panel instead, which is supposedly a more energy-efficient H-IPS [shrug]. I've noticed 'S-IPS' is sometimes used very generally to mean any modern IPS...
As to the colour gamuts, many punters would probably prefer a native sRGB display to something wide-gamut, especially if they are concerned exclusively with online and other digital media, rather than editing for print production. That said, the Dell's sRGB mode is supposedly not bad, and the dithering issue has been fixed with rev A01.
Right now I'm leaning towards the Dell U2410 myself, especially if I feel I can get a handle on dealing with the wide gamut through colour profiles. Of course, I dread getting a dodgy panel, but as I said, I rather doubt HP will prove much better in this regard, especially considering their lower price point.