After playing on 9ft tables anything smaller feels like a "kiddie table". I've never met anyone who's game got worse switching from a 7 to a 9. The people I've encountered (league or otherwise) that tell or show me have seen their game improve from playing on 9 foot tables.
It's my humble opinion that your game will improve in more ways then 1 if you get a 9ft home table
I agree with this, with one exception -- and that is if you play 8-ball on the barbox.
Ts Renfro succinctly states, you're going to need to do some half-table drills to make sure your cue ball control is precise, since in the case of 8-ball on the barbox, you have the same number of balls, approximately the same-sized pockets (this depends, of course), but in HALF the table real estate.
With 9-ball, it's a wash, and actually, I find 9-ball on the barbox almost a kiddie game. Even though there's only half the table real estate, as you remove balls off the table (assuming there's no troublespots / clustered-balls you need to deal with), the game gets to be easy; almost like, <dink!> <dink!> <dink!> (i.e. no need to let your stroke out as you often do on a 9-footer -- on a barbox, you can just "poke" at the balls and be reasonable with cue ball control).
But in 8-ball on a barbox, if your opponent has a significant number of "soldiers" on the table, you have to be more precise with the cue ball than on a 9-footer. The "windows" to navigate around your opponents balls are tighter than on a 9-footer (remember, it's that half real estate thing). An inch or two "not enough" or "too far," and you're snookered / in trouble. Pair this with the non-standard cue ball found on most barboxes (i.e. Valley barboxes -- either overweight [Dynamo] cue ball or magnetic cue ball), and this compounds the problem.
In general, though, having a 9-footer will be a boon to your game, not an albatross around your neck.
The same people who say practicing on a 9' table hurts your barbox game are the same ones who look at me and complain that my handicap isn't high enough. Well... I practice solely on 9' tables so I guess they're wrong.
Indeed. Those that say playing on a 9-footer will hurt your barbox game may be coming from that "I only play on a barbox and actually myself don't have the stroke/skills to play on a 9-footer" world. Many exclusive barbox players have this stance, and they are, of course, incorrect. The only thing is that cue ball control thing in 8-ball (I described above).
But if you play/practice 14.1 or one pocket on a 9-footer -- or even do half-table drills -- you'll definitely have the "touch" it takes to transition over to the barbox very quickly.
If you get a 9-footer, you might want to think about getting yourself a quantity of 1 each of the following types of cue balls:
You can practice with these cue balls -- even on a 9-footer -- to get accustomed to how they react.
-Sean