It's quite a coincidence you should ask this today, as last night I swapped the Custom / '59 pair back into my '96 LP Standard in place of the Seths. I don't know whether this will be a permanent change, as I love the Seths, but now I have Ants in my LP Classic I thought I'd like to give the Custom another spin. Not sure whether I want two vintage-output LPs or one vintage and one hot-rodded. Decisions, decisions.
I have played the Custom in my Standard on a couple of occasions previously, and liked it a lot. It is hotter than the PAF-style pickups I normally go for, but not so hot as to sacrifice versatility. It is quite a bright pickup, but the mids are strong too and the bottom is tight and chunky. I find rolling the bridge tone control back to around 7 or 8 gets it just right.
When I have played the Custom in an LP with a band, the first and most obvious thing I have always noticed is how my tone really cuts through. The second thing I have always noticed is the big silly grin on my face as I wheel out all my favourite classic rock guitar cliches.

Must be the way the mids are on this pup, but you can hear yourself so clearly and the notes just leap out at you. Sustain and harmonics are suddenly more easily available. Compared with an alnico 2 pickup the mids are noticably harder, but for a ceramic the Custom still cleans up nicely when you roll back the volume.
In comparison with the 498T, I would say the Custom has similar output, but is less harsh sounding and better balanced. It has full mids, but no upper midrange spike. I find that spike in the 498T detracts from the bottom end and makes it sound tinny. None of that with the Custom - it rocks in an LP!
Not sure whether Billy Duffy used a Custom on The Cult's "Electric", but that's the kind of tone you get with one in an LP. I hear Dan from The Darkness has the Custom / '59 set in some of his LPs too. It also does a good Ace Frehley impression when pushed!
I consider myself mainly a PAF-type guy, but if I want to turn up the heat a little the Custom is my ceramic of choice. :newangel:
Whether you go Custom or CC, just get the other magnet too and you'll be all set!