From the built in help file of the firmware
'Xmit Power - This value ranges from 1 - 251 mw, default value is 28mw. A safe increase of up to 70 would be suitable for most users. Higher power settings are not recommended for users due to excess heat generated by the radio chipset, which can affect the life of the router.'
You are right, it helps improve distance constraints. On a previous Linksys (v1) I owned, I turned up the power and noticed I could pick up my router at the top of the street (using the 'tools of the trade' as my job entails network security)! It's trial and error until you find a level that does the job. As long as the security is configured appropriately then the extra 'reach' should not be an issue. Unless I'm one of your neighbours.......
