the xsi x addon is somewhere hidden at their site, is not easy to find.
but is free.
Hash am has been used for realtime games. I wouldn't advice it for that...splines based thing..you can't play with smooth shading inside th esoftware really...the workaround is import -or make there- a low poly model forcing all the corners to peak instead of the standard curved thingy. But u see then as solid faces, actually. And not exactly the same.Obsidian games sell an x plugin that is proved to work quite nicely.
I don't think is ideal, but in some cases, ie, someone that mainly is gonna do much hi res, but some low pol, could buy it.
My personal choice is XSI foundation -yep, it has all I need for any game task- Is hard and complex to learn, but just for the everlasting reason: like blender -but no so much- is different to other UIs. And in more range than Blender, is a very, very in depth and advanced tool...any advanced package is complex to learn. IE, I learnt Character Fx in hours.
After that, my second choic is Blender.
of course, my favourite choice would be Max7 and latest character studio 4.x, no bundled with max, not like before.
But hey, I'll never have that money.
Ts is ~ XSI Foundation in price. Hash is 299$(but u'll want to add the cost of the obsidian AMTEX plugin for x files). max is 3.500$
Blender is free (what costs is pain to learn, and it has some features out: for instance, in character animation, XSI is way better.)
TS UI is somehow quicker to learn. I have purchased ts 4.3 since sometime when the 79$ price offer was.
One thing I love of it is its great booleans. I don't like its...er...ehm...undo...

But yep, is quite intuitive and has some advanced modelling tools, and helpers, even 4.3 has many of them.
TS 6.6 I think even requires you to buy the gamepak if you want to export bones and weights.
Also, I don't like it's control of weights. To do really good low pol animation, you strongly need to work at vertex level. Well, as far as I tested in every ts new version -I'm that fan of testing- it has tendons and muscles, kind of envelopes, but actually a lasso selection or weight painting solution with numeric input of weights...
The way I'd deal with it in ts will require anothe rplugin (ts ones advantage:they're cheap) a 10$ paid by paypal called skin modifier. The name seems be given in purpose. Is somehow a simulation of the wonderful Max skin modifier (I like it since Max5) .And gives you the control needed.
So, if I would have purchased TS instead of XSI Foundation, I no doubt would buy that cheap one skin modifier, and the x ful export one. As the included native, is dx7 I think. At least no bones and weights+animation. there was that truex one, but I tested with ts 4.3 -reason I bought it mainly- and it did not performed the same once exported...not sure if was a tendons modifier problem...
Gamepace maybe a better deal for games, as it comes with the x export, and I think is finally a good one, but not sure in this point. There have been some problems with exports, as u see in their forums.
XSI ripped stuff...hmm...hair rendering for AVIs, etc...advanced cloth, advanced rigs. But XSI bones and joint pinning is already better than anything I have seen till now, except max character studio, to my liking at least.
I mean, Foundation is usable for games, perfectly.
BTW, imo is quite harder to learn than TS.
But fo rthat they are giving away 5 DVDs...
I think they have made a great move.
But I am not a fanantic of any tool.
I know I perfectly coul do only with blender (Now that I can handle it. I just wanted some more char animation power and purchased then xsi) , perfectly with gamespace, and even with hash am, provided training my self in getting used to how the flats will behave in smooth..something I often already do while in modelling in Wings3d.
I'm quite against the idea of thinking that a package is totally horrible...
I don't like the char animation tools of TS, I hope they improve them seriously, but i like it's way to guess the correct position of bones inside body as you rig. The actual building of skeleton could be way improved, the handling of bones for animation also, and the weights...what I have said. But other nice thing it has (I tend to like ts features , but not the thing as a whole, it suits me as I use many tools in a project.) as nice, is it has bone pinning.Not joint, but a full bone (2 joints).Is better only joint, but is something (you could also make a very small bone to be the pinned one) Way better is XSI solution for all this.
BTW, as I said, ts looks mor einmediate to learn. I dunno how unexperienced enough 3d users would deal with a package like XSI or Blender. I love them both, but I don't know...