Hi Steve
Didn't saw the Nugget Detector Guide until you posted the link here; have to say that was pretty much what I was looking for. Best guide that I've read so far regarding this matter, thank very much for putting it all together.
For beginners like me, the Minelab X-Terra 705 that you shortlisted seems the better option to go for.
Have also come across White's Surf Pi Dual Field Metal Detector which it seems primarily designed for beach metal detecting, but the dual VLF and PI combined into a single the dual field MD; seems to be one of the better alternatives to single field detectors. I'm not sure how effective it will be for gold prospecting but if you have information or suggestions please say something about it...