You can get some very realistic numbers, in the UK at-least, simply by comparing syndicate share adverts, since they are not run at a profit.
Let's assume 400 hours per year, and looking at adverts in AFORS, I get the following figures
C172N: £3250, £65/month & £75/hr, 12th share = £39k.pa (£98/hr) for a £39k aeroplane
Jodel D120, £2000, £69/month & £48/hr, 6th share = £24k.pa (£60/hr) for a £24k aeroplane
C152, £2250, £30/month & £45/hr, 20th share = £25k.pa (£63/hr) for a £45k aeroplane (seems a bit overpriced to me!)
PA28-161, £2850, £85/month & £75/hr, 12th share = £36k.pa (£90/hr) for a £34k aeroplane
PA28-140, £3600, £90/month & £60/hr, 6th share = £30k (£76/hr) for a £22k aeroplane
Jabiru, £5750, £55/month & £35/hr, 1/4 share = £17k.pa (£42/hr) for a £23k aeroplane
Sky Arrow, £10k, £60/month & £25/hr,1/4 share = £13k.pa (£32/hr) for a £40k aeroplane
Arrow, £6k, £97/month & £90/hr, 6th share = £43k (£107/hr) for a £36k aeroplane
PA38, £900, £40/month & £55/hr, 20th share =£32k.pa (£79/hr) for a £18k aeroplane
Zenair Zodiac £4950, £32/month & £23/hr, 7th share = £12k.pa (£30/hr) for a £35k aeroplane.
CTSW, £15k, £40/month & £80/hr, 5th share = £34k.pa (£86/hr) for a £75k aeroplane (the whole deal sounds overpriced to me!)
Dynamic, £8k, £59/month & £45/hr, 10th share = £25k.pa (£63/hr) for a £80k aeroplane (personally I'd say it's worth about £60k)
So, except for the very high performance ships (the CT and Dynamic) we seem to be looking at a substantially lower overall cost for the small "hot ships" like the Sky Arrow, Jabiru and Zenair (an average of £35/hr) versus an average of £67/hr for an old technology 2 seater, and £93/hr for an old technology 4-seater.
I couldn't find any numbers for a 4-seat Jabiru or Dyn Aero, but if the 2 seat comparison holds good (modern aircraft about 52% of older 2 seaters with similar performance), I'd anticipate around £48/hr.
The other interesting comparison here is that the older aeroplanes you seem to be paying about the purchase price, to annually fly 400 hrs. By comparison, the newer ones around half. So, the purchase cost will proportionally be much higher. On the other hand, I can't see any calculation not still showing these modern aeroplanes better value in the long run, so long as the hours get flown. On the other hand, for a sole owner flying 50-100hrs per year, almost certainly the old "heavy metal" aeroplanes will work out best value.
G