Full frame? Does size make such a difference?

Whilst on holiday, I went into a duty free camera shop with a chum who wanted a new zoom lens for sport photography. As he peered through the expensive glass, I was tempted to handle a Nikon D750. I did and was infatuated with it, as it felt so good and looking through my 24-105 lens made my wallet twitch with a desire to free my credi card. It was a very close call but self control prevailed. Now, I'm seriously considering going "full frame" as most of my lenses are okay for such s beast. My D300 has served me well, and it even bounced from a height onto a concrete step earliest this year, and survived. I'm tempted to keep it snyway as it's probably worth all of half a crown now! 

Anyone out there that can offer me advice? Is the difference really as much as I might hope for?  

Somehow my name has disappeared off the previous post so I am re-posting here --

Hi Rod, I can only give you my impressions based on my Canon EOS 5D Mark I (full-frame, 12.8 MP, announced in 2005) and my Canon EOS 7D Mark I (1.6X crop sensor, 18.0 MP, announced in 2009), so please bear in mind my cameras are somewhat 'dated', but I think the comparisons are still generally valid.

PLUS for full-frame : Even though my full-frame camera is older, the image noise is noticeably less than my newer crop-sensor camera,  particularly at higher ISO settings. I think this is due to the greater size of the pixels on the full-frame sensor, allowing more light to fall on each pixel.

PLUS for full-frame : The full-frame camera will give the widest possible angle of view for a given focal length i.e. A 28 mm lens will appear quite wide on full-frame, but the same lens will be equivalent to only 45 mm on a 1.6X crop sensor camera.Your wide-angle lenses will stay wide, which is very useful if you do landscapes and cityscapes

PLUS for full-frame : For the same subject and framing, the full-frame camera gives a shallower depth of field, simply because you have to get closer to the subject to fill the frame. This is a definite plus for portraiture.

PLUS for Full-Frame : Bigger, brighter viewfinder.

MINUS for Full-Frame : More expensive.

MINUS for Full-Frame : Generally not as fast in frames-per-second because the big mirror has more inertia. Sports and wildlife photographers will need to pay serious money to get a full-frame camera doing 10 frames-per-second.

MINUS for Full-Frame : Lenses suitable for full-frame are generally more expensive than the lenses designed solely for crop sensor and will be physically larger for a particular focal length / aperture.

MINUS for Full-Frame : Physically bigger and  heavier camera body.

Thank you Edward. More fodder for my grey cells.

When I do plump for a full frame, I'll certainly hang on to my D300 for a while at least, as my 10-20 Sigma is a wonderful lens and to replace that will prove expensive.

I certainly take note of what you say.

The wheels are turning.........   

Hi Edward; another good thread, well done!

As for the avatar not showing it times out after an hour, which is why it didn't show... "I must type faster" lol