We are debating 10 vs 9 ft ceilings for our basement ( due to additional cost). Contractor suggested 9 ft poured and 1 ft cinder blocks to minimize cost of 10 ft poured. Any cons with this decision? I know cinder is not as sturdy ( more cracks, potential for water, etc ) but don't know if one row will be that noticeable or big concern. We are planning on finishing the basement eventually.

Thanks!

And in my area many basements were built this way for exactly that reason.

Here's how the savings works: Forms typically come in either 8 or 10 ft. heights. Concrete forming companies charge a premium for bringing in, setting up and stripping the higher forms. So, to get greater ceiling height in the basement, the builder will add a row of one or two concrete (not cinder) blocks.

Now, personally, I prefer the greater lateral strength of poured vs. concrete masonry units and the speed of construction. However, I have added two rows where there was a mistake in the excavation depth or the customer decided they wanted greater ceiling height than the plans showed. (You have to watch the roof height in that case!)

Local costs may well change the balance.

As for basement heights: If you want eight foot clear, you must go to nine feet to conceal ducts and services. However, if the basement is deep below grade, you might reconsider ten foot heights, unless there's a walkout on one side. When you have to stand on a step ladder to even reach the sill of a basement window, more than a bit of claustrophobia may set in.

The description "concrete blocks" is barely any more accurate than "cinder blocks."

I have worked on older houses that had actual cement block.
Straight Portland cement with no filler.

They are incredibly hard after almost 100 years.
The stopped even .27 caliber powder loads cold after barely 1 inch of penetration.
1/4 inch carbide tipped masonry bits only lasted a single hole.
We ended up using diamond bits and water.

Cinder was an early filler in blocks.
It was cheap, and an original 'recycle' type idea (coal power plants still have tons of cinders to dispose of even now).
It also resulted in blocks that ate any metal in contact very badly.