I agree that the real deal is best, but I cant afford to stock up on real sai for all of my students so often we have students ready to join the class but can't because its gonna be a week or two until their own sai are shipped and delivered. The idea is if the polypropylene ones, like the ones from century has listed as "trainers" are just good enough to get started for a week or two, then those are cheap enough I can buy and provide them until my student's sai are delivered. But if you cant even practice basic handling with them then I don't see the point which is why I ask if anyone hase ever used them.
If these are going to be your in-house weapons just for temporary beginner use, it should be OK until the students get their own real thing. Something is better than nothing in the short term. I learned the longest kata in my system with a 4 ft. plastic broom handle, though I did have a lot of prior bo experience. Along this same line, I also practice weapons kata without weapons, finding it very beneficial, but I wouldn't teach it that way.
Balance point is VERY personal, as well. So what you think is too forwards I might well find just peachy.
Are you concerned the difference in weight would be an issue? As for price, the cheapest I have ever seen were made of rubber.
I have not, but I can imagine not wanting sai like that. Learning to open and close the sai correctly is a basic skill, and that requires the ability to use the weight of the sai to 'flip' (I hate that word, but it's appropriate here) the sai from open to closed.
I’m not a fan of training with mock weaponry unless it is a genuine safety issue. Even then, there are ways around the safety issue that still gives you the feel, weight, and performance of the real thing. For example, using a sword made from quality steel with a solid hilt, with the simple modification of rounded edges and point. The weapon is real but the danger of a serious cut from poor handling during the learning process is all but eliminated.
