I haven't tried handling the R8 but I DO have an R4, which is a compact SLR along the lines of an Olympus OM-1, which is a sweet caemra but equally small...that was the point.

If it is a problem for you to hold the smaller cameras, may I humbly suggest you spring the same money and buy a Leicaflex SL2-- it is a big larger and easier to hold if you have larger hands, the controls are all mechanical, the camera is built like a tank and it can use all the current and past R lenses.

It also has, many feel, a superior ground glass focusing screen AND the match-needle metering is supremely accurate (once the camera is adjusted for new batteries) and much simpler and more instinctive to use than the later automatic systems.

the shutter on an sl-2 is also really really really nice -- mechanically damped, ultra-quiet, it was made to be as nearly as smooth and quite as an M as possible, and they came darn close.