In an earlier post entitled G.A.S., I spoke of the evils and detriment of looking for the latest and greatest piece if gear. In that article I mentioned that there is also a positive side, that positive side would be growth. Given the fact that over time with practice your photographic skills will increase and there is a chance that you will out grow the gear that you started out with. Over time that kit lens with the variable aperture will begin to frustrate you, you'll have gone beyond its viable usage. Where do you go from this point? Thankfully we live in a day of easily accessible information. Countless reviews can be found in numerous locations. You will also find that there is a wide range of reviewing styles from the highly technical lab controlled tests of DXO to the sniff tests of Jared Polin of Fro Knows Photo fame. All of the sites offer great information you just have to chose what best works for you, personally I prefer the real world tests but I can also appreciate the pixel peeper style reviews. One thing I like to do is to check out customer reviews on sites such as Amazon or B&H . These reviews will give you an unbiased review but there is still a better way to find out if something will work for you, rent it. There are a number of sites to rent from with a wide variety of gear at a fairly reasonable cost.
Renting also allows you to expand your creativity and continue your growth as a photographer by giving you access to tools that you wouldn't even think about purchasing.
Do you want to make your world look tiny using a tilt shift lens but you don't feel like shelling out the $1700 for a highly specialized lens, well you can rent one for a week for around $100. Makes sense to me. Beyond this aspect you can use a rental as an opportunity to see for your self if a piece of gear is right for you.
Growth is fun and exciting, getting new gear is also fun and exciting. Growth will lead you to new adventures and exciting opportunities.
You and only you can decide what you need, educate yourself and ask your fellow photographers what they do and do not like about the gear that they have. What matters the most is that you Shoot What You Love Love What You Shoot.