I have had some good results from Delta 3200, but you're right - 10x8 does start to show up the limitations.(posted 8576 days ago)I have recently been trying out the New version of Delta 400. It is important that it is the new version (Lime Green writing rather than Dark Green, and a red "New" flash on the box) - as I have not had quite so much success with the older version.
I have pushed this film up to 1600, and found it very good indeed. Sharp, and fine grained, with a good range of tones. Admittedly I am using 6x7 film, but you should still find it good on 35mm.
I've found good results processing in Ilfotec-DDX, but have also seen excellent results using XTOL.
Hope this helps!