While the X70 will sometimes track out weak peeps from deep/small targets, I have found having it on to be beneficial. In all but the heaviest of iron contaminated sites the signal response on iffy targets is improved substantially with tracking on.
Running beach mode on land takes some experimenting. I don't always like it! For one thing, the timbre/pitch of the iron tones changes and becomes very annoying to listen to. The advantage is better signal response on deeper targets buried near iron/trash. Targets not heard in normal mode with lower sensitivity settings boom in using the beach mode at the same setting. The result is you can slow your sweep speed down to almost a crawl allowing the detector to analyze each target with minimal depth loss. It is not the same as running in normal mode with higher sensitivity settings and a slow sweep! I dig more iron "foolers" this way at my old sites but also more coins!
However, like I mentioned before, the iron tones drive me nuts in beach mode so notching out the worst offenders becomes a necessity!
Tom