For a very long time and until now, there have been models of Microsoft Ergonomic Keyboards, with all the classic PC keys, just with a split layout of the keys.

I have used such keyboards for many years and I have been content with them, even if a couple of years ago I have switched to a more compact completely split keyboard, without a separate digit pad (for 2 reasons, a closer position of the pointing device and easier transport in my luggage, due to its smaller total size, to be able to also use it instead of the non-ergonomic laptop keyboard).

Unless I am mistaken, the Microsoft versions are all single slabs of hardware with a slight space between the halves. By split keyboard, I want two separate pieces of hardware I can arbitrarily position to fit my body. I maintain a solid 12 inches(30 cm) between the pieces on my desk.

If you want completely separate halves, with the 104/105-key formats the right-hand part would be much larger than the left-hand part, which is inconvenient when you want to move or transport it.

You can achieve the same effect in a more convenient way by buying any of the many keyboards with separate parts for the hands, together with a separate numeric pad, which contains the third part of a classic 104/105-key keyboard.

The only remaining difference from the classic format is that on such keyboards the home-end and PgUp-PgDn key pairs are typically on the same vertical column at the right edge of the keyboard, instead of being side-by-side, but it is easy to become accustomed to this arrangement, which actually makes them easier to reach.