Advice on Introducing a new rider to a green broke horse?

[Caz]

I would like to introduce my horse to a different rider other than myself. He is 3 now and needs some hours under saddle. No one else has ridden him apart from myself and I haven't come across the right person I would ask that of yet. I'm considering sending him off to a trainer for a few week or so just to work with them to ease my mind. Its a big step to see how he will respond to another rider... and I have to admit I'm going to be jealous to take a step back and have someone else work with him, I have really enjoyed the fact I have been his only rider so far aside from the kids having pony rides! I'm leaning toward a female trainer but would you think that it may do him some good to have a male work with him too??? Its really scary ;P I'm a sook and he is my baby... so its important its someone who's methods are similar to mine and that they listen to what I've done. Ultimately after having done it alone with him I'd prefer to work with another person if I ever broke another horse, I think it would be so beneficial for the horse. Any guidance or opinion is welcome... If you have started your own horse or are a trainer when do or did you introduce a new rider?
Thanks