I have had a good time with the Ace series.
Started years ago with a 150.
Bought a couple 350s before AT Pros were being used much, I believe they had just came out at that time. Made some neat finds with the 350,some where Pro users hunted.Running it in jewelry mode with headphones and tones on deep targets similar but not the same as shallow ones. Recoveries by tones only for deepest targets i.d..a delicate mellow chime in the silver range is a personal favorite.Two silver dimes beyond 7 inch blade recovered,( the guard passes top of hole beyond seven, and they were beyond it,not going to say how far without proof but beyond seven, l.o.l.)
The Pros have a solid following and reputation.
Given a choice I,d take a pro with a 5x8 coil for myself in high trash areas but your areas soil and mineral may differ.
Larger stock coil for low target number areas and to cover previously worked areas.
If a 350 is available with out buying it give it a run. A test on your test garden if you have one. The less discrimination the better,knock a little iron off and back sens a couple notches from full as a rough start.Then to the field! Dig a dozen targets getting familiar then take a small tour of an area you have worked well before to see whats different. Then of course a new area.
Have fun.