I've never had a custom board in my life & I'm 43yo...I think basically coz up until 5 years ago I never had more than 2 boards. A small wave board & a big wave board & I was living in places with good waves with no crowds. Always needed a quick replacement after snapping a board kind of scenario. Not against custom boards & I'll get one one day. Will havta have some epic artwork on it to celebrate the end of my custom board virginity haha
Personally I think a local shaper will help you with providing a board that is suitable to the conditions your surfing. Its awesome if they have surfed with you over time & noticed certain nuances of your style that modifications of surfboard shape will benefit your personal style. If they don't know you, telling them where you surf can be beneficial too.
It really comes down to having the right board for the waves your riding. Some places are just sucking heaving pits peeling down the line requiring some rocker for late take offs & length depending on your paddle power. Some places are fat powerless waves or waves with big fat sections to negotiate. Riding the right board suited to the wave makes a huge difference. "Malibu" wouldn't have been so great if the surfing evolution started with short boards & "Pipeline" would have been pioneered a lot earlier if everyone wasn't riding longboards to start with, you know apart from those planks of wood the Hawaiian dudes started on. Good luck with that...
There are so many options for boards these days & I think branding makes it easier for the shaper & the buyer. This fairly new ideology of having nic-named boards is awesome. There are these categories of surfboard, designed to do stuff in certain waves already customised to the weight/ability of the surfer & I think that is awesome. You find a board that works for you & you can replace it by specifying that nic named board & size. Then make adjustments based on that design.
But yeah it doesn't always work...I have a 6'2 Hayden Shapes Psychedelic Germ thats modified from the Shred Sled that I use in head & a 1/2 to triple over head clean waves that I bought off a 90kg guy for $400 who loves his 5'10 Hypto Krypto, but the Germ just didn't work for him. Its an awesome board provided waves are clean & the offshore isn't too strong...I think its probably the equivalent of the Firewire Dominator vs the Hellfire.
At the end of the day it comes down to where your surfing & your ability. If your an above average surfer, refining your shape in quality waves can be of great benefit or if you would like something a little more special it really doesn't cost much more money for the custom experience...My problem is I'm just a little too rough, I can't resist that end section over shallow reef or straighten out when someones dropped in. Its best for me to grab a second handy between $350 & $550, coz I go through too many boards these days trying to match the right board to the conditions. Could also be a mid life crisis trying to keep up with the young blokes

Comes down to what you want/need. Nothings gonna come closer than a custom & its good to have people out there that might love your board if it doesn't feel quite right for you...I'm sure that happens to everyone eventually & its interesting to hear what people like about your old board