The Axiom has nice graphics and is Android based. The issue is, it does not support older protocols such as NMEA 0183 and Seatalk. This is a big deal as it requires a total upgrade. The Seatalk system was excellent for its time and even today, it is perfectly sufficient for instrument data such as GPS, waypoints, routes, autopilot, sensors (wind, depth, speed). If you have these sensors, then you need to upgrade all of them.
One option is to use a Seatalk to Seatalk(ng) converter and it converts some but not all data. If you have nmea 0183 then make sure you get an MFD that supports those inputs.
Then there is the radar. If you have analog radar, then anything above the Classic E80 requires you to move to digital radar. The new displays use LCD lighting which is more efficient than CCFL lighting used in the older displays but you lose that efficiency with the more powerful radar (i.e. the lowest digital radar is 40 watts vs. 28 watts for the analog Raymarine radar, the difference is 1 amp which is not insignificant).
Let me give you a example:
Typical boat with ST4000+ autopilot, ST60+ instruments and classic E80 displays + analog radar. You upgrade to any new Raymarine display. Connect the autopilot via Seatalk to Seatalk(ng) converter, you lose some functions. Next, the new displays are 16:9, so you need to get at least a 12" display to get the same picture as the E80 - expensive. You need to upgrade the radar - higher power consumption. Need to run new cables, need to get new charts. Either you do a total system upgrade or you forget about it.
Good luck.
SV Pizzazz