I am up to 318 worked, first with a Kenwood TS-440S and then with a Yaesu FT-857D.
Got 139 worked on 160 which is a band that really challenges a rig. The trick with raw rig performance is to understand signal levels to keep the rig in a receiving sweet spot. I'm sure I would notice the difference of a better rig on the low bands in crowded conditions or when there are big thunderstorms. Same on all bands in contests. But DXing doesn't actually challenge rigs with poor electrical specs very much... not most of the time, and especially not on the higher bands.
I use Ham Radio Deluxe keyboard shortcuts to make up for the huge deficiencies of the '857D in the "buttons and knobs" department. Split and reverse buttons are mapped to my keyboard, including a special button for CW DXing that goes to the pileup-side VFO and opens the filter wider and then goes back to the DX station and narrows the filter.
Top of my list in a new rig is true dual receivers, preferably with phase-lock capability. Might be nice to have some kind of panadapter display, and it wouldn't hurt to have excellent close-in dynamic range, but that's mostly because I want to continue low band DXing. For the low bands I'd also like something with a real RX antenna input.
Hey Dan...... sounds like you need a new Icom 7600
. I have one on the way. Scheduled for Friday delivery. I cant afford it, but hey..........
73, Gene AF3Y