QuoteI used to stick to 40mm frontages but now have switched mostly to 60mm for earlier periods or a combination of 30mm and 60mm for late C19th onwards.
It's depths I have more trouble with especially pikeman at the level or 45 degrees!  I don't like the empty space in front but if the pikes overhang the base they always get damaged

This.
I'm not a fan of the extra work involved with pikes.
Where I do use them I ensure they're vertical to avoid that overhang problem.

As for basing, I saw the revolution that came with Impetus, where a base was an independent unit.
Some would argue that Volley and Bayonet was there decades earlier.
Some might make the case for DBA (Though it's need for a cohesive line rather reduces the independence).

What really seemed to capture the imagination of hobbyists was the potential for diorama bases.
Not having to pfaff about with 8 or 12 elements was also a bonus to some players.

Obviously such basing doesn't work for every era of warfare, or every scale of battle.
It usually requires some means of status tracking for casualty steps.
It also calls for a bit of imagination where rules incorporate formation changes especially march columns.

I'll close by saying it works very well with 10mm size figures.

I am just going to paint a load of stuff and worry about the basing afterwards....

 

QuoteI am just going to paint a load of stuff and worry about the basing afterwards....

 

Not a bad approach! Means you can try out some base configuration and see how it looks. 

QuoteI used to stick to 40mm frontages but now have switched mostly to 60mm for earlier periods or a combination of 30mm and 60mm for late C19th onwards.
It's depths I have more trouble with especially pikeman at the level or 45 degrees!  I don't like the empty space in front but if the pikes overhang the base they always get damaged

Yeah, I love the look of pikes at different angles but does result in some frustration with overhang or extra depth. Suspect all upright is the easiest approach even if less visually impressive. Works well for pike and shot style warfare but loses something with the ancients.

upright pikes all day long if I am honest for me personally these days.

off to paint a few bits and bobs this afternoon

Quote...
Yeah, I love the look of pikes at different angles but does result in some frustration with overhang or extra depth. Suspect all upright is the easiest approach even if less visually impressive. Works well for pike and shot style warfare but loses something with the ancients.

One option is to use the lower angle pikes in the rear ranks

There's relatively few upright pikes in the Flodden range that i'm working with the majority being at an angle or level.  But they are lovely little chaps so I decided to increase the depth of the command bases by 15mm to accommodate levelled pike in the second row and put non pike armed officers amongst the points in the "dead" space out front.