One downside for older trainees is family understanding the commitment necessary during training and after.
Don't get too hung up on the age thing. Yes it's true age makes it harder in general - harder to learn a new way of thinking, harder to absorb and integrate the plethora of information and rules into a coherent whole, harder to achieve the right balance. And while it's also true that statistically you're pushing it up hill, the key point is you're being measured against a standard. You at 35 will have to work harder than you at 25 but maybe the 25 year old sitting next to you will be finding it harder, in the end it all comes down to how each of you individually performs against the standard.
All you can do is give it your best shot and keep on plugging away.