We love our RP6.
To be fair, it’s a brilliant turntable and certainly good enough, by itself.
We’ve ended up with two turntables in our house.
We love them both. They both do things slightly differently and we’re okay with that.
In any case, could never let our RP6 go, as it came as a special gift, ( from my best mate, my wife).
Always felt our RP6 + NEO psu + Ania Pro + Aria phono was similar level to the LP12 in its original guise. The main difference perhaps that our LP12 seemed a little warmer, more organic, more natural to what we expected from music being played. ( To be fair, maybe a bias from years of playing vinyl ).
During 2020, we were moving home and this offered the opportunity for music in a second room.
We already had a pair of Epos ES14’s and the LP12, both still original from late 80’s. So, we decided to add Naim Olive shoe boxes - from the same period - in between, to create a vinyl first system, ( that is, vinyl as the leading source). Maybe a nostalgic celebration of the golden age of vinyl. A system with a lot of synergy. Audio reproduction items perhaps made for each other. We then decided to upgrade the LP12, to modern specifications. But it was also important to us, that outwardly our “old fruit box” was kept all original, the way we knew and liked it.
If you are interested, these are two separate stories, told here.
Story (1) : Refreshing a venerable old lady. Good for another 30+ year.
Story (2) : Project Olive
In our case, arriving at two turntables, was more an evolution of hifi pieces into two systems, than any deliberate decision, per se.
Differences between a Rega TT and a LP12 are maybe becoming more obvious to you by now, from your recent demo’s. For us, the Rega style is open, neutral and analytical. However, the LP12 has developed a long way in recent years, the many additional updates to the original design have maybe made the LP12 sound more modern. Maybe more analytical and resolving in the same way too.
Our LP12 - in its updated form ( version of Selekt ) - is now the best source in our house, analogue streaming or otherwise. Even more so, since we added a SuperLine for phono duties. Now, maybe more resolving and analytical than its original form. It really digs deep into vinyl to retrieve the music. It’s a revelation to hear so much from recordings. But it also retains all the boogie and warmth and “connection to music” of the original style that we liked so much.
To my way of thinking, there is a lot of subconscious thought that goes into selecting a turntable, a mix of emotions, some of which are connections that go backwards to previous experiences with vinyl and using record players. As an example, for me, the LP12 is how a record player should look. A fluted LP12 is such an attractive object. So completely agree with @JonathanG …
So, yes, definitely worth the investment.
Although, to be honest - with LP12 bits and pieces - doesn’t have to cost as much as maybe you think 
Lastly, in both cases - over time - we have tried to aim for a well rounded and nicely balanced system. Both of our turntables are used within the context of a coherent system.
Good luck with you own journey.
Hope that helps.
R