Though I've grown to more or less enjoy writing Domino applications, I always feel like this is in spite of the tools, namely Designer. In a lot of ways, Designer has improved significantly over the last couple versions: as long as you ignore the speed, the Eclipse-ified Java and LotusScript editors are miles ahead of the antiquated previous ones, and it's handy to be able to switch to the Java perspective. However, so much else makes it a drag:

• It's a Windows app. I use a Mac, so there's simply a big hurdle to using Designer. Parallels has smoothed the process greatly - running Notes in Coherence mode means I can use my preferred OS while still getting work done. However, it means that it's a big to-do whenever I want to make any tiny change in the code. For day-to-day work stuff, I can get a lot done in the Mac Notes client, since I put in a lot of work to make managing client web sites doable without going to the design side, and the Mac client still lets you edit views and agents. However, there's no XPages editor, so I can't use that for serious work.
• It has a mind of its own. For some reason, a new clean install of Designer I made the other day got it into its head that opening any database should involve recompiling every XPage and Java class. Sometimes, it turns off "Build Automatically" for no reason, and then turning that back on also requires a full recompilation. Sometimes, it just holds up all user actions while it does... something for five minutes. What's it doing? Beats me.
• How many times have I seen this window? A billion?
  Removing a database from the project list has about a 30% chance of causing a crash and quitting Designer has about a 50% chance. Sometimes, saving a form will do it. Sometimes, walking away from the computer to get a drink is enough. And every time it crashes, I have to dismiss the dialogs and check the task manager to get rid of any residual processes, such as an instance of nsd pegging a processor, then relaunch Notes and get back to the environment I had, which is not a speedy process.
• I'm not that crazy about Eclipse. DDE is better than previous Designers, yes, but Eclipse is still a giant beast with the same sense of style and simplicity as the monstrous Java language that spawned it. On the plus side, the blue look that IBM came up with is actually rather attractive compared to the standard Eclipse UI, but little quality-of-life things are a drag. For example, how do you specify how many spaces a tab should take up visually? It's in a couple places in the preferences and you have to set them all, including buried inside a weird sub-preferences dialog for messing with your Java formatter. And how about changing your code syntax coloring? You have to go to a dozen places, one for each syntax type. Compare to a text editor like TextMate, where you can swap between packaged color schemes with a drop-down.

That's enough for the rant. So what is there to do about it? I give this problem a thought from time to time, and I don't think there's really a great option, but there are some places to start. The real key to any alternative scheme is DXL - using that, you can (more or less) view and modify design elements freely. I've toyed with this notion before - maybe a web UI that lets me pick the DB and design element I want so I can tweak the DXL manually for when I want to make a quick change but don't already have Windows or Designer open. It would mostly work, but it would take a lot of work to make it practical.

There's a big sticking point, too: XPages. If you export an XPage to DXL, you can see that the exporter basically punts on it - it's exported as a generic "note" type with Base64-encoded binary fields. I haven't run the field data through a decoder, so maybe one of them is the XML "source" of the page, and maybe it could be made to work, but that just raises more questions. Would that require updating the other binary fields in some way? Would importing it with a DXL importer cause it to generate and compile the Java representations? What about generic Java classes? Would those work with DXL and would they be compiled?

I'm starting to get an idea of what would be ideal and almost practical, though. One could write a WebDAV server (possibly with a complex servlet, a small web server to the side, or other trickery) that represents the design elements as editable files in a folder structure similar to the Java perspective view of the database. Traditional files and image resources could be edited as-is (which I think the built-in WebDAV server does), but design elements could be represented just as DXL and then re-imported when modified. Even if it doesn't support XPages, such a scheme might have a lot of promise and wouldn't be reliant on Designer or any other IDE.

If I ever get brave enough to delve into WebDAV or frustrated enough with Designer, I might just look into it myself.