While not the way I would do it the photo in the initial post will work fine as an unbalanced network as long as long as your total backbone length is less than 40m (131 feet). It is always better to run a balanced network as expansion is often easier, although it is not always possible to run a balanced network considering where the displays and MFD are to be located in relation to where power accessibility is most convenient.
The i50/i60 displays will convert the analog transducer data into a format that can be read by devices such as a Tri Data Displays, i70 Instrument Display, or an MFD on the STng backbone without the need for an ITC-5. If you don't use the dedicated i50/i60 displays (speed, depth, wind) and use all i70 Instrument displays then you will need to use an ITC-5 to convert the transducer data into the STng format.
About a year ago I upgraded My older Raymarine ST series instruments with i50/i60 displays and an Axiom MFD without replacing any of the existing transducers and it works perfectly well. I have the depth, speed and wind data displayed on the right side of the MFD screen overlayed on the chart data. A few months ago I did a similar upgrade on a friends boat and put an i70 at his nav station, again using the existing transducers without an ITC-5.
The i50/i60 displays will convert the analog transducer data into a format that can be read by devices such as a Tri Data Displays, i70 Instrument Display, or an MFD on the STng backbone without the need for an ITC-5. If you don't use the dedicated i50/i60 displays (speed, depth, wind) and use all i70 Instrument displays then you will need to use an ITC-5 to convert the transducer data into the STng format.
About a year ago I upgraded My older Raymarine ST series instruments with i50/i60 displays and an Axiom MFD without replacing any of the existing transducers and it works perfectly well. I have the depth, speed and wind data displayed on the right side of the MFD screen overlayed on the chart data. A few months ago I did a similar upgrade on a friends boat and put an i70 at his nav station, again using the existing transducers without an ITC-5.