When I asked MS about the amount of space available in the Take Control / IRIQ, here's the response I got.

> The overall macro limit is 64 and each can have up to 99 steps. If you
> have a lot of devices and activities already you may be limited in the
> overall number of macros. It depends on how many buttons those devices
> and activities contain and if a lot of learned buttons for devices are
> present that will also take more memory. If an "average" amount of
> buttons are present, the limits are as follows:
>
> Device limit - 15
> Button limit per device - 64
> Activity limit - 32
> Buttons per activity - 26
> Macro limit - 64
> Steps per macro - 99

Personally, I have the following and have not yet seemed to hit any memory limit.

27 Activity screens (avg each screen half full)
11 Devices (~275 total buttons)
29 Macros (avg about 5 buttons / macro)

Jim