you are correct that the dies are the heart of reloading and not the press. all the press does is give you the mechanical ability to get a case into a die. in fact presses are not needed at all. I have loaded thousands of rounds with Wilson dies and when I started with them I tapped the case in with a hammer before I got an arbor press.
my only complaint with the lee is that it does not cam over. I have one and I think it is limited to what can be resized in it.
my first press was a lyman c press bought in 1965 and it is still going strong. my go to press for stuff larger than 6br. and up to 300 win mag.
I use a hood press for the small stuff and keep the the lee for odd stuff like pulling bullets. you can buy these used quite reasonable. last year I picked up a spare lyman for 20 bucks and 2 years ago bought the lee for 10$ at a gun show.
the smaller o presses will give some extra strength and make you feel like you can do a little more. and if you have real big cases they are needed. if you get into forming brass for wildcats they may be necessary. but so far I have got by with my lyman c press making wildcats.
there are some great alternatives also, like the forrester co-ax which is strong and has easy to change dies. perhaps even easier than the lee breech block and you don't need extra blocks to put the dies in.
so to answer your question outright,,,maybe. if you have trouble sizing cases or plan to get a larger caliber it may be worthwhile.
but just cause the lee is a lee. don't bother to upgrade.
