Upgrade from x-50

Hello everyone, finally time to move up, my teenagers have been hunting with me, so we have a, BH SSII, Tessoro sil u-max and my minelab x-50
so I am familiar medium range machines, and have found a-lot in the last 5 years.

I usually would be considered a coin-shooter, but ground balancing to work at salt water beach is important (wife loves beach, in-laws live near beach)

I have really done a lot of research and here is where I am.

I really like the way my x-50 works (I have 3 coils for it) but it falls short on ground balancing, depth, back light, no threshold.

Price range could go to 800, new or cared for used, If I go to my max I will need to sell some (kids are loosing interest)

So will a ML 705 get extra depth ?, I haven't been able to find a direct comparison or use one to compare

used Safari , hard to find and they sound a-lot different in you-tube videos

Mine Lab SE, some used, are just cheap enough, should I go for it and sell the x-50 and 3 coils

Other choices ?
Please any hands on comparison info would be helpful, thanks