This will work...sort of. The problem is that individual culms will live about seven years, and then die. If you keep wiping out new shoots, you may ultimately end up with a plant that is fairly dead in the center and without much growth on the edges.

You're not actually doing rhizome pruning: that term refers to reducing the root mass (usually of wayward runners). If it were my plant and I absolutely couldn't let it get bigger, I'd divide it. However, with a clumper, this can be fairly hard because the root mass is very compact and woody. The last time I did this it took two of us about a 1/2 hour pounding on a sharp shovel with a sledgehammer until we had spit off a big chunk.

Hmmm, probably very good advice to divide it. BUT what a job it would be. Especially the larger of the two I have. It's well beyond the capability of my husband and myself. I know it'd take two very strong guys and a lot of digging just to get it out of the ground, and then it would be absolutely a monster job to cut off a piece for a division.

Last year I decided to give away a big Drep. khasianum. There were 4 people who wanted divisions, and it took those 4 guys several hours to manage it.

I'm beginning to think I should never have chosen bamboos for my small garden. I've got about 4 Borinda fungosas that are proving great screens, but they are even larger and could use the same treatment (division). I guess I'll have to budget for this project every couple of years. (Or give them all away and start over with something that needs less expensive maintenance.)

You don't need to take it out of the ground to divide it. In fact, that's a bad idea that compromises the plant. You just need to split off a piece and dig that out of the ground, leaving the main part of the plant intact and undisturbed. This is a fair amount of work, but much better than shocking the whole plant.