But I am curious about why the 7 foot tables seem to be so popular, especially the Diamonds. From what I read here, if you don't have room for a 9 footer, it seems that the 7 foot table is the preferred way to go. Nobody much seems to consider an 8 footer; looks to me like it's either a 9 or a 7. And there even seems to be tournaments played on 7 foot tables.
In general, the room you have to put the table in dictates what size table is "best" for you in that room. It seems in cities these days that the average "ancillary" room is too small for a 9-footer, a squeeze for an 8-footer*, and pretty tolerable for a 7-footer.
(*) certain obstructions like a corner or column may make some shots "unfriendly" requiring "house rules" or short sticks to "even up" the whole of the playing surface.
So I'm wondering what's up with the 7 foot tables? Is the geometry of the table somehow more similar to a 9 footer than an 8 foot table would be? Logically it would seem to me that the smaller the table, the less any skills on that table would transfer over to a regulation 9 foot table but obviously my thinking must be wrong.
The physics of smaller tables is "just a bit ""off"" ". The diamonds are places back from the nose of the rail a certain amount to compensate for the forward roll of a naturally rolling ball and the distance was specified for a 10-foot table. After a naturally rolling ball bounces off the nose of the rail, it arcs-forward a bit due to the roll changing the angle of departure. The smaller the table, the less distance this effect has to "play out" and the shorter the table plays. 3-rail corner to corner shots are the most obvious point, but corner to other side to corner single banks also manifest the effect. Most players just "get used to" whatever effects their table has and adjust rather than figuring out the physics.
Smaller tables need somewhat tighter pockets than larger tables so the the "basic shot" difficulty remains rather constant. 7-foot tables with bar box pockets are too easy and allow one to play without needing to develop the proper precision in his/her skill set.
8-ball on smaller tables is more about clusters and delicate position. The player who can read, break, and avoid clusters has a distinct advantage on smaller tables. While these skill are less necessary on larger tables, they remain part of a well developed skill set, nonetheless.
Cloth:: a high speed cloth (Simonis 760 or even faster Simonis 300) on a small table will cause you to develop a mastery of delicate CB control, or will drive you batty, or both. I have Simonis 760 on my 8-footer and the local bar box has regular felt and one of those larger CBs; the combination is that the energy imparted into the CB is pretty close between my home table and the local bar box, in making the shot, avoiding interference, and traveling the proper distance to the next shooting position.
With proper choice of pocket size and cloth, you can make a smaller table have similar difficulty as the larger "pool hall" tables--you can't get it exact, but you can get in the same ball park. And if you get it in the same ball park, your game transfers from home to hall efficiently. My 8-footer is as large as I can fit in my room, but I have the pockets shimmed, the corner angles recut, and faster cloth. This translates to the local bar box, and also transfers to the pool hall league tables rather efficiently.
The problem is that few who choose the smaller table get the table optimized for the game they need to develop and just use the table "as delivered" until they tire of it, complain that it does not play "correctly"*, is too easy, too hard, ..... and go for a bigger table, or change houses for one with a bigger room and fit an appropriate table to the new room.
(*) for any definition of correctly you desire.