TiVo & V6 run TiVo-firmware, TV360 run Horizon-firmware, thus the two are different.
V6 offers radio either via the EPG (thus recordable) or via the Radioline app, TV360 only has the app - this us one of the functional differences for which there is no mitigation.
I use a V6 so am unsure on whether there are any options to change the text colour, although if you've already found the "large" option I suspect that's the answer. TV360 does rely heavily on voice control, that's a design choice by VM.
Conversions from TiVo/V6 > TV360 are voluntary, but are also irreversible. There have been a couple of cases on this forum where users who could demonstrate medical issues and mis-selling by CS, were offered a reversion. My understanding is that the process to revert is quite "heavy duty" and requires a lot of manual work by back-office teams, and thus VM require a pretty good reason to even consider it. A simple case of buyers remorse is highly unlikely to cut it.
I've moved your post from the "chatter & natter" section of the board, which is rarely staff-monitored, to the TV360 section where staff should pickup sometime next week. Wait around and see what they say, but there's no promises.