I have been around private server comminuties for a long while now (i used to be very well known as a client modder and hexer in the eAthena community) and all i can say is good luck trying to get the idea to work.
If you can safely assume that every person who will use your patch has a fully updated and clean client (i.e. not tainted by 50 other private server patches, most that were badly made) then you will be ok but this doesn't happen. What you are usually dealing with is a complete muppet who has no idea what client version they have, whether it is updated or not and what garbage they have in it from other private server patches. This always leads to major headaches for the server operator as they try getting the big pile of mess to work.
On top of this players don't really like the whole idea of patches as the instructions usually say you have to have a specific client installed (link usually given), then the patch on top and people think "well, i have Cabal installed already so why?". It is simply too much messing around for people who are usually too lazy to click more than one link or use their brain when installing the client.
One standalone client with everything in it solves all of those problems in one hit and the only real problem is with people who have slower connections or low transfer quotas on their internet. Patches really only cater for those people and those people are generally the monority. Ever server i haev ever operated i have been asked for 1-click clients that don't involve any messing around and i have no intention of ever messing around with "server patches" because they are more trouble than they are worth.