Is it sensible to have children with a man over 40?

[Hunteress]

Any advice from older parents...
I have always wanted to be a mother and desired a future where I can create a family with someone I love.
I think I found that person.
He is intelligent, kind, generous, incredibly funny, talented and resourceful, hard-working, courteous, the list goes on... And he's gorgeous 😍

The one thing that plays on my mind is that he is 40 next year and I am concerned with starting a family this late in life, about the things that could go wrong/what milestones might be missed.
I've read a bit about advanced paternal age and it's effect on DNA stability and chance of miscarriage/mutations. From my understanding fertility decline impacts men in a similar, if less sudden, way. That's one worry.
Another is the concern that he would be into his 60s or 70s by the time the children would be of an age to consider a family themselves. I'm worried that he wouldn't get much time with any grandchildren...

He has a daughter who is 10 years old already to a previous partner. He is open to more children and shares some of my concerns.
I feel I have plenty of time and don't have the same considerations, as I am in my mid-twenties (25).
And I struggle to know weather to pursue this or weather these things will impact my children's life in a negative way... And weather the age gap will widen (emotionally, energy-wise, etc) in 10 or 20 years.

Any advice out there?
It's very appreciated!

I think that's a bit extra.

Also a little bit much. We can say the OP should swerve being with a man of 40 when she is 25, without being nasty about him. She's not 16. She's 25!

Around 67% to nearly 80% of people aged 70 and older in the UK live with a long-term health condition or multimorbidity (having two or more chronic illnesses).

Age gaps... I'm well aware they can be an issue. And please don't think I'm not treading into this carefully.
In the past I dated a man who was 17 years older and was an incredible human being. But we did end up parting ways due to the power dynamics involved when one half has lived almost 2 decades longer.
I stand by the fact that that man was not creepy or opportunistic in any way shape or form.
But I'm also aware that this man is different. In all ways.
Which may mean we don't run into the same obstacles. It also means, he may have motives.

I can't know until I see... And for now I'm being very careful.

This is big for me.
I've always steered clear of men with children...partly for my own life journey and partly because there have been studies on how step parents can potentially negatively impact a child's development.

His daughter is with him 50/50 and they love each other to pieces. He is a very attentive and engaged father.
His daughter comes first to everything. He supports her admirably in all ways from all I've seen/heard.
He is on amicable terms with his ex and they co-parent in a very friendly way. From what I understand the split was difficult but they worked it out.

Having a ten year old in my life. Not an issue whatsoever. However, I think there may be adjustments I'd have to make to my expectations of time together, because he will need to prioritize being Dad before being lover.

It would certainly complicate the situation if you went on to have your own child/ren with him. Many many people do negotiate this successfully, but many others find it very hard. And as you say, he would be spreading his 'dadding' thinner.