Mag; You did not state your purpose/reason for moving up to the .454.........that would probably answer your question.
The 45 LC is a great cartridge and you can get a little more get up and go by reloading. On the other hand, the 44 Mag at standard loading has taken every game animal on the planet.
I had shot the 44 Mag for well over 50 years and had not found it lacking for any purpose. Unfortunately damage to my wrist put an end to shooting the 44 Mag. I can still (barely) shoot a 44 Special, and for my purposes now, I do not find it lacking in any regard.
I guess it all boils down to "need" or "want". If you feel a need for something more powerful than the 45 or 44, go for it, or if you just want a 454 to play with thats good too.
I have found through experience that anything larger/heavier than a standard Super Blackhawk, Mod 29, Redhawk, etc, is a lot of weight and size to be dealing with under the normal conditions of daily carry, be it on the street or in the woods........also, you will have to deal with the higher recoil generated by the 454, and if you cannot control the gun and hit what you are shooting at it will serve no good purpose, so, there are trade offs that should be taken under account before making a choice.
Waffletops advice should be taken into consideration: take a test drive of a 454, see if you can deal with it, and then make your final decision.