I've had both machines, first a V3i for a couple years, then a VX3 for a season. The "guts" are identical, the software features are the only difference. No, the VX3 does not have polar plot. I did not miss it, since I found it did little to aid target ID that the signagraph and three-frequency pinpoint didn't already give you. What I did miss on the VX3 however, was the lack of adjustable tones for the Tone ID. On the VX3 it's all or nothing: one separate tone for each VDI number or one single tone for everything. Most peop[le, including me, prefer 3 or 4 tones that each cover a range of VDI numbers, so this is a big drawback on the VX3. Also, is the lack of any manual ground balance control on the VX3. The V3i has sort of a manual override, where you can loc the ground balance point, then adjust it incrementally via the Offset to manually follow the ground. The ground balance on the V-series is critical and sometimes tough to get right, and without the Offset adjustment ability of the V3i, properly ground balancing the VX3 can be maddening sometimes.
It's kind of a shame about the VX3, it's like a V3i with one arm tied behind its back on purpose just to create a marketing price point. Still though, since you're basically getting the same performance from the VX3, it's the better the deal. The additional cost of the V3i is pure profit margin since the cost of production is the same for White's.
In the end, I'd say go with the V3i. I actually really like the VX3 and is at a sweet spot of adjustability compared to the overly complex V3i. But the lack of Tone ID options and ground balance Offset control, are deal breakers for me.
