It depends on how you define top-tier.
I got a teaching position at a top tier IB school with 2 years of IBDP experience. However, I would not describe that school as a top tier school. Though I have seen it appear regularly on numerous ISR top tier school lists.
I did go on to teach in a (what I would classify) solid top tier school after 5 years of teaching IBDP

Positive experience.

CRS education. They are running a fair in Shanghai around this time of the year.

Good school but not so good location !

Where does this leave JIS ??? Joint adventure ..... ??? Translates into what ?

any asian school provide housing.

Any opinions / views / comments ?

I have used their services, in fact i have been in SE Asia for the last 4 years and i got my current teaching post thru Teachanywhere. I also know of another 2 teachers who got their current teaching posts with them. To me they were very professional and helpful.