Pretty sure gilberts on Sharrow Vale don't dip anymore, but might be wrong.
TH Goode on Chippinghouse/abbeydale did do, but thing they might have gone now too.
We used a guy on Pearl Street, opposite where the old Vine Pub was. No idea if he still operates.
Our doors did warp a bit, split a bit etc, They still need a lot of sanding and filling too, so its not the time saver you think it might be.