I think you would be very pleased with this set up.

Any lens that has a range from 18 - 200 has to compromise, and the Tamron one is no different.  However it has many advantages too, one of which you have already mentioned. The Tamron lenses I have seen have been good quality and can produce good results.

There are some members here who use this lens: Nathalie is one who uses it as a travel lens taking it all over the world.  Perhaps she could give you a guide to its strengths and weaknesses.

 

And every one said, 'If we only live,
We too will go to sea in a Sieve,---
To the hills of the Chankly Bore!'
Far and few, far and few, Are the lands where the Jumblies live;
Their heads are green, and their hands are blue, And they went to sea in a Sieve.

Edward Lear
http://www.nonsenselit.org/Lear/ns/jumblies.html