As far as the Tow Pac goes it has to be your decision. Try and find some people out there who have them and can give you some good feed back on them.
I personally know three people who have had them. Two are still riding them and would not have anything else. One went ahead and triked his bike after a couple months. Said he just did not feel comfortable on it.
If the tow pac is what you can afford and it keeps you enjoying riding then I say go for it..