Another good safeguard is to spend e.g. $200 for an employment attorney's time to review the contract and explain to you the ramifications of breaching the contract and the possibilities of the employer making a demand against you. He/She might be able to draft a rider to the original contract that might protect you if the company you go to work for folds or sells the aircraft, etc. If their is not an equitable proration, do not sign it, IMHO. I have heard several war stories of these contracts not being enforceable in court because of material misrepresentation, bankruptcy, etc. Again, $200 with the lawyer will answer all of your questions and prevent possible litigation down the road. Venue would be an important consideration here as well.
I believe that the industry standard for a contract is one year, whether it is for training or a relocation agreement. It is sad that professional pilots need to sign these (dependent on the operator), but I do empathize with the operators who are trying to control their costs and stay within the confines of their operating budgets. Turnover costs represent 50-60% of a candidates salary, to hire and train a replacement pilot.
Keep in mind, that if this is a large management company that you are considering, their actual costs (minus travel expenses) to type you in the _______jet could be considerably less than the dollar amount signed on your contract. Most likely they will be charging you retail cost of a full service contract with one of the large training service providers. Their actual cost for your training can be significantly less due to contracted/volume discounts with the training provider(s).
Good luck on your endeavor. Hopefully, this is a company that will treat and pay you well and reward your loyalty/longevity.