I have owned a standardbred (pacer) for almost 20 years. He passed away at the age of 29 this past spring. I still miss him. He was my first horse and there wasn’t another like him.
Standardbreds are a lot like brenderup trailers. People who have never owned one, and only know what they hear, will tell you not to get one. The people who have owned them and know them will tell you they are great. And that’s what I will also say. I love my STBs. Mine was super smart (like evil-pony clever) and willing and very forgiving of me especially when it came to driving.
I think that any problems driving would come from making the assumption that STBs are trained to drive at the track. I’m certain there are some who have good training (it depends on the trainer)–and I often wondered if my old STB was one of those–but I think the majority of the time they pretty much hook them up and go. When I have visited a huge training track in NJ they hooked 'em up and jumped in the bike while the horse was already jogging down to the track.
And yes, there are some (but IME these are in the minority) who are born to pace and getting them to trot is a 50/50 chance and just forget about cantering. I did have one for a short time who was like that. She’d pace in the walk. She wouldn’t trot and she wouldn’t canter. She’d even pace to and after a jump which I thought was pretty talented. But IME most of them would rather trot.
The only time my old horse would pace was on the Xcountry course (I evented him first and did fairly well at it) when he lost his balance. I never had a problem with him pacing in the dressage ring. I don’t know about CDEs. Of course you trot in the dressage test but does it matter what gait you do on the course? I would think there might be some times, when for a moment the horse may break to a pace if he’s unbalanced but if the gait doesn’t matter out of the dressage ring then I don’t think it would be a problem. Hey my lusitano paced once on a trail when a backhoe started raising its bucket right next to us without warning. The poor guy didn’t know where his legs were he was so startled and for about 2 strides he paced. LOL
My only caution would be to assume your STB has never been broke to harness and start from scratch like you would any other horse. I never had any issue teaching my old guy to drive. In fact it was very anti-climatic and he took to driving like he’d been doing it his whole life.
And then later on, last year, I found an old racing bike and drove him in that because he has arthritis and couldn’t do much. I thought a little walking would help and I thought he’d enjoy the activity. I think he did actually and I hooked the bike up to him and walked him up and down the road once or twice a week. He was a perfect gentlemen.
Actually, the first time he was in it (I had been too impatient and didn’t take the tires all apart to check them) the tire blew. It sounded like a gun shot right in my ear. My old man started scrambling forward and trotted back for home but within maybe 30-40 meters I had him back to a walk. I don’t think I’d be alive to write all this had I been driving any other horse. He was definitely my guardian angel for 20 years.
And he standing on the sidelines and watching me show is not his thing.
He thought the only problem I MIGHT have is collecting his trot in the dressage phase. But I don’t think so, I rode him in dressage for many years and did quite well in the lower levels.