JM, right now the only complete age-creation pipeline (that takes you from modeling through texturing and export to playable URU ages) is the plug-in for open-source Blender developed by the people based at
www.guildofwriters.com.
With the impending release of Cyan's plug-in for 3DStudioMax, and its code, several things are likely to happen:
1. People that already use Max will be able to export their work to URU as soon as the plug-in operations are understood.
2. The code will be applied to improve the existing Blender plug-ins.
3. The information in the code will be applied toward the creation of plug-ins for other modeling applications. Several fans have already expressed interest or commitment toward creating exporters for Maya, Lightwave, and Truespace, for example.
Also, keep in mind that these days, there are many means for exchanging data from one 3D application to another (with varying degrees of accuracy and completion in terms of texture-mapping and animation, for instance). What that means is that it won't be so important what application you choose to create ages. For example, I imagine that once the Max plug-in is released, some community members that own Max will offer their services for translating models made in other apps into URU-ready ages.
If you're going to be a serious agebuilder, you're going to be spending enormous amounts of time working with whichever modeling application you select.
Before you worry about getting your data into playable form, you'll likely spend
months learning the software and then modeling your spaces.
So before you launch into agebuilding, do some careful shopping-around to decide which 3D application is best suited to your preferences, your temperament and working style, and your finances.
Truespace and Blender are the only free full-featured modelers available right now - and you already know about Max's free Gmax version.
All the for-money apps have demo versions you can download and test to see whether they're right for your needs.
So check them all out - it's a big decision you're going to live with, and many of us have found that it's not that easy to switch back-and-forth between different apps (they can have vastly different GUIs, keystrokes and workflows)
My guess is that whatever means of initial creation you select, there will soon be one or many options to get your data into URU-playable form.
(one very exciting feature of Truespace I just noticed is this: real-time online collaborative modeling!)