New camera time?

[Phil]

Hi,
Currently I have a Canon 700D crop sensor camera.
It's served me well, I love using it and it's been all over the world with me.
Mostly coupled to a rather flexible Tamron super zoom lens. (10-200)
Sometimes I shoot macro and rather more recently a Sigma 10-20 lens, which I do not like so much. The images never seem very sharp.

I love to shoot at night, stars, traffic, towns and cities, as well as the sea and dramatic waves. I use ND filters a lot as really enjoy long exposure photography.

About a month ago, my trusty 700D got soaked. I was photographing a stormy sea when a wave took me by surprise. My own fault and lesson learned.
Since then there are spots on some of my images. I clean them up in photoshop so it's no big issue, but knowing the effects of salt on circuit boards, I don't hold out much hope for the future of my camera.

So, having had the 700D for nearly three years, I've been thinking of upgrading and here I come looking for advice.

I want to see an improvement in my photos by upgrading.
By that I mean so I can actually see and justify the costs involved!
I want a weather sealed body for shooting by the sea and better noise control.
I have my eye on a Canon 6D Mk2, but at £1400 I want to be sure I'm doing the right thing.
I know that I need to consider weather sealed lenses as well.

Any advice?