I have always grown bush beans but I have been reading about pole beans because they are recommended in my mini farming book.
Pole beans grow on vines, and need to be trellised or supported in some method. They are indeterminate which means they produce all season and end up producing more beans per season per plant but not all at once.
Bush beans on the other hand do not need trellised and they are determinate they all come on at once within about 1- 1 1/2 weeks for a large harvest and then you can pull them and replant beans or something else or just be done for the year. A lot of canners prefer the bush because you get a huge harvest and then can them at once. I have easily gotten 80 qts and then given almost that much away with a few rows of bush beans.
As far as space probably pole beans are more effecience because if you put them in with say your corn it takes up no extra space at all. You won't have to bend over to pick either. I am considering them.
We switched to pole beans a few years ago. I don't mind them being indeterminate. I just freeze what we can't eat after each picking. They sure are easier to pick (A selling point for me.) You will know what you are getting by the catalog or package discription and name.
The packets should say what kind they are. I do both. Blue lake pole and blue lake bush are the two I often do. The bush beans mature about 3 weeks before poles start. We have mild springs/summers/fall with high's in the mid to lower 70's, so in a short summer, pole beans might not reach their potential harvest. Bush beans are a good standby with certain yield.
Since bush beans only require about 60 days to produce a crop, gardeners can often (as 'Dorie says) pull the old plants and sow more bean seed in the same ground. I have done this but it is really risky since the 2nd harvest will come right up against the first frost.
It isn't worth the risk here but I usually follow peas with beans. I can easily get the peas in and out early enuf.
So, bush beans have very quick and concentrated production. During the heat of summer, bean seed sprouts and seedlings grow well. Then, a 2nd crop can be harvested.
Wasn't it last year that Vfem planted a few black beans (bush dry beans), allowed them to fully mature, harvested her crop, and replant those beans? She parlayed a few beans into a basketful by growing 2 generations in the same year !
With pole beans, the plants will likely occupy the same ground through a long season. They are productive but it is hard for me to imagine that they would produce as much as TWO crops of bush beans.
I don't mess with pole beans any more, blue lake bush are my bean of choice.
I found that the work of trellising was too much for not any better yield.
I think your choice may come down to how you want to use them. If you are planning on canning a fair amount, bush beans are probably the way to go. You can get a lot of production over a short span. If you just want a few to eat on during the season, pole beans may be your answer.
Since you are asking about space efficiency, you possibly don't have the room, but if you can, try planting a few of each type and see what you think. You have a long growing season in Austin, but the summers can be fairly dry. You may wind up doing a lot of watering, especially with pole beans. You and your water bill may be happy to have the production over and done with bush beans. But I really like fresh green beans from the garden all season.
I do mostly pole beans since I use my garden fence for the trellis. I'll can what I need then keep one section picked and watered to produce beans for the table all season. The rest I let go to seed and use those for dried beans.
Last summer my bean production was weird, due to the unusually hot dry summer. My bush beans (Black Turtle dried beans) made before the heat set in, but the pole beans (Blue Lake for green beans) did not. I usually have all the green beans canned I need by early August. This past summer, I had to water the pole beans all summer and did not get my first green bean production until October. With all the water I put on them during the hot dry spell, those were expensive green beans. This year I'll have some bush beans for green beans.
Fortunately, watering is not a problem for me. The landlord pays the water bill. Last year I gave them some of the Kale (about the only thing my garden produced in any quantity) and they were happy. It's when I water the lawn that they might say something.
I am always surprised at how well pole beans do for me. I have 2 of those fancy trellis that kind of look like an obelisk. One gets planted with scarlet runner beans and the other with 3 blue lake pole beans on each of the 4 corners. Since these beans go up, I like the fact that they are planted in a partly/shaded area, but they still get sun once they get going.
I don't particularly like the scarlet runner beans because of their rougher texture so those are mainly for the hummingbirds. The blue lake produces quite a bit. Enough for the kids and I to have for lunch several times a week and for me to freeze alittle. This works because it's just my husband and I.