I’m not a fan of ISH for myself so I do not know as much about them. Most are just not my type of ride but they are certainly many a good one and are certainly the right type for others. I will say, I wouldn’t breed your mare unless you would be happy to get an exact copy of her. I’ve yet to breed a mare who I was looking to change temperament or hotness…granted I like a forward mind and forward ride. Wanting to improve on your mare is every breeder’s goal, but I wouldn’t ever bred a mare unless I hoped to at least get just like her.
I have one Dutch/TB broodmare. I have a lovely 4 year old out of her by Royal Prince. Not a 4* horse but a VERY fancy all rounder. And likely could go up to 2*. But so could her dam. He did improve the rideability and kept the dam’s top movement. That said, her full brother now 3 is VERY different from her in type. He is nice too but HUGE fancy tank where 4 year old is short coupled beautiful little sports car (but super super easy to ride). Breeding can be a crap shoot.
I like the lines on Royaldik and he was quite impressive to me in person. The Royal Diamond lines from him are known for their good brains but he has enough blood when crossing on a mare like yours. Of Holsteiners…I just bred a TB mare to Quiet Easy. She suited him and I have liked his offspring. GK Calucci at Hilltop added bone to my mare’s filly by him…and a good mind. My mare has an exceptional mind but I like that he was a jumper stallion ridden by an amateur and he is lovely in person.
But honestly…there are a TON of nice stallions out there. If you do go down this fun but very expensive black hole of breeding…make sure you do you research on your mare and her family and the the stallion and his. I personally wouldn’t stick to one registry…but would be looking for what family and sire I think would be best with this mare.
Where are you located? It is getting late in the year to start breeding…you don’t have too long of a window.