GCSE options - sciences, history and/or geography

They went at a faster pace because there is more work to cover

This was probably because the top set did triple science in the same time as everyone else did combined science. It sounds like OP's school uses an extra option block for triple science, so this won't be the case in her school.

When my DD1 did triple science, the top set all did it and they were separate from the double award lower sets. They went at a faster pace because there is more work to cover. DD2 did double science and stayed in her second set. You just do not do the same in depth learning which is why triple is better prep for A levels. Double is no barrier to A levels but check gaps in learning are not a step too far.

Not sure debate really matters in a science class. It is really more about ability and pace of learning and A level aspirations at GCSE level.

He's worried double cert science won't be as challenging as most of the top set kids will be doing single sciences.

The syllabus doesn't change depending on who is doing the course, so doing combined doesn't miraculously become easier.

In the 'old days' of triple being done in the same time as combined I'd agree that there does become more likelihood of more able scientists doing triple so maybe the top grade 9 issues not being discussed so much. But I suspect that is less of the case now that it more generally needs a slot.

The triple course isn't de facto harder, it just has more topics. (DD has switched from doing combined to just biology, the extra stuff is no harder than the content already covered.)

However if expecting to do science A levels I'd think hard before not doing triple, as it is likely triple knowledge will be assumed as a starting point.

DD was also doing both Drama and Food Prep&Nutrition.

Drama - the thing to watch for is group work. If you DS might have any issues working with others then avoid it. Otherwise it makes a good movement break between other more sedentary lessons.

Food - has a good mix of practical & theory and is a useful life skill too. Some of the theory is really quite sciencey. Will require practicing outside of school.

Drama & Food both only had 1 written exam which would have made summer of y11 a bit lighter. The exam schedule can be brutal for those doing a full set of traditionally academic subjects.

I would add that Geography is good with sciences and is useful for environmental science at university. So that keeps more doors open. Also good for Civil/Environmental Engineering when combined with Physics and Maths. So in his position triple sciences and Geography keeps doors open.

My DDs both did Drama but: their school was superb at it. Amazing teachers and the academic dc did it. Brilliant for confidence and no one messed about. Very different in some schools so check results. Ditto Nutrition.

So mine did exactly what RedSky has said - maths, chemistry, biology, physics, English language, English lit, history, geography, Spanish & German. If food & nutrition had been available they’d have done that instead of German. They’d have enjoyed the light relief I’m sure!
What does your DS want to do?

Our school pulled GCSE food & nutrition in 2018 as exam boards ceased to offer the A level. This meant that neither of my DDs had a non-academic subject. They both did 3 sciences alongside geography and history. It was & is absolutely fine. I don’t think there’s more workload in geography or history; they’re pretty content heavy. Be aware that drama is a lot of work - writing analytical essays about plays, theatre etc. It’s certainly not a light option.
Choosing dual science is 2/3rds of the 3 sciences so providing he obtains decent grades he can go onto A levels. There’s obviously more of a jump as he’ll have missed that 1/3rd in the sciences he takes to A level.

What does he want to do after GCSE? If he's interested in science A Levels or a scientifically based career, it would probably be better to do triple science, although in theory it is possible to move to A Level science from double science (if this is something he might like to do, you should check at his current school/local sixth forms).

Both combined and triple science have higher and foundation papers, so if your DS is able in science he will be entered for the higher paper and will study harder content, regardless of which he does. It is, of course, probable that more of the more able scientists will take triple science, however others will also choose to take combined to allow them more freedom of other options. If it helps, in DD's year (average comp) 10% of the year are in line for taking the higher combined science paper.

Taking geography, history and triple science (and presumably also English lit and lang, maths and maybe a language) is a very heavy academic load and I think taking drama or Food would be a good idea for something a bit different (at DC's school you would have to take at least 1 less academic subject). Though your DS should be aware that there is still a fair bit of writing in both! I don't know a lot about food tech but drama has group work, so there is a slight element of risk as you might be put in a "bad" group. My rule of thumb would be, unless there is a very specific reason in terms of keeping future options open, DS would be best advised to do subjects he thinks he will enjoy most.