I also started with Lee molds back in the 70's. As with everything Lee, you may have to futz with it a bit to work correctly. Not a huge issue to me, I like to tinker.
Late 2000's I found this site, read about the higher end molds, thought I'd give em a try.
Discovered MP and my bank acct has never been the same ! (and RCBS, Lyman, etc)
What you get with these molds is much better selection in weight and diam. And hollow points !!!
Also, at least MP has molds that are as exact a copy as possible of Elmers and others
Lee has their cutters made to last the longest - just about all the edges are rounded.
High end - sharp edged driving bands, the front of a SWC will cut a perfect round hole in paper or ? (whatever)
MP and NOE have hollow point molds that are as easy to cast as solids.
And there is the pride of ownership - high end are a thing of beauty, esp the brass MP
I bought a 2 cav HP from MP never having the intention of casting with it - just wanna look at it
A fella could cast a whole life with Lee - not a problem.
But eventually ya owe yourself a "splurge".