Custom shards aren't an issue generally speaking, IF you allow for easy patching. Offering a full custom client download is a start, but the make things easier you need to keep patches small rather than changing maps, animation and gumps all at once, that causes your patches to grow leaps and bounds, just pick one at a time and go with it for that patch release. Then as time goes on, move into another area and make updates and release that, etc.
I was against patching at first, but once I realized that OSI couldn't keep up with me and never will, I moved into patching a custom client. With just about everyone and their brother having broadband connections these days, it takes what, maybe 5-10 minutes to download a 1GB zip file? That's nothing, go grab a drink, use the bathroom, come back and it's done. What's the point of every single free shard all being the same, with the only changes being to scripts they are using? Scripts will get you a fair share, but being creative with custom content helps more. 😉