Within the last six weeks, I've planted two apple trees, two pear trees, two plum trees, and two nectarine trees in my yard. Here's a diagram showing my current layout (I added the periods to preserve the spacing):

........A........Pr........Pr........A........


....N.......Pl..................Pl........N...

The trees are spaced four feet apart. The apples were the first in the ground. I planted them about 12' apart with the idea of letting them grew to their full 12-14' mature height (semi-dwarf). I soon realized, though, that I didn't have any other good spots in the yard (small lot, mature trees, etc.) for the pears, and so I did some research and stumbled across the Dave Wilson method of tight spacing and pruning to maintain small tree size. So, rather than move the apples, I planted the pears between them (hence, the 4' spacing). I added the plums soon after, and the nectarines were the final addition.

So, while I like the balanced layout, I'm thinking about grouping the apples and pears on one side and plums and nectarines on the other with the idea of fostering better root cooperation. I could also space them a little more closely. Given the situation, would I be better off leaving the trees where they are rather than putting them through the stress of transplanting? Or, in the long term, would the trees be better off if I regrouped them?