Here's my take on it.
The Explorer & Safari share the same coil and accessories for the most part and there are plenty to choose from.
The Safari is kind of a dumbed down Explorer steered towards relic hunting but is very capable of pulling coins as deep as the Explorer.
Two models of the Safari but latest Safari is the quicker responder with a faster processor.
A good used XS, EX II or maybe even a SE can be had on the forums for a real good price and I strongly suggest buying from detecting forums over eBay ... for TRUST issues mostly.
Simply put, nothing out there equals the Explorer platform for coin shooting, that's what it was designed for and the only other machine that compares is the Etrac.... but the jury is still out on that one.
The MXT is by far my choice of any Whites offerings, YES even over a DFX because it's a more rounded machine in my opinion. It's also the relics hunters choice in Culpeper, Va. where the ground is almost nuclear hot. It does a good job at coin shooting, just doesn't quite equal the Explorer for coins. The MXT can be used for nugget hunting and you can forget that with a Explorer unless you hunt where the nuggets usually come up in good size. The MXT also has a ton of coil choices to choose from ... so you can't go wrong there either.
With the Explorer, Safari and MXT ... you have the option to add the Sunray pinpoint probe .... hard to live without once you use it.
On the other hand, the XTerra 70 is another fine choice, it does well in hot ground, is a great nugget shooter, coin shooter,relic hunter and I've had good luck with it on beaches too.
Also has many coil choices ... but no Sunray probe is available because the coils have chips in them specific to frequency changes. Still a great lightweight machine with outstanding battery life.
Just my 2 cents worth ... hope it helps
Mike