Although I signed up for 25 mgps down plan, I have only been getting about 15 mgps. So I just upgraded from 25 mgps to 75 mgps thinking I could really improve my performance and guess what? I get about 15 mgps down and 4mgps up. I spend an hour on the chat line with a rep testing it and boosting the signal. No help. Then he tells me that I should go wired to see the improved speed. Well that's really inconvenient. So he says my other option is to buy the N router for $115. So I get roped into spending about $40 to upgrade - which is NO UPGRADE so they can sell me anothjer $115 to actually get what I paid for. Great strategy Verizon. Well I guess I won't be renewing.
You should really use a Wired connection whenever possible with FiOS. Speed and Wireless don't mix together. Wireless N will help you achieve the 75Mbps, but don't expect to see that. Many Wireless N connections deliver 40-60Mbps in many realistic conditions.
You are however, free to go back down to 20Mbps if you don't want 75Mbps. You should also be able to contest the additional fees if you were on an older, cheaper package with enough effort.