Just a thought, but before you commit to upgading (mind you, I'm not saying you shouldn't) you might want to figure out where you're losing most of your time. A lot of people lose considerable time when doing crosses. Even with a dropweight you should be able to string a racquet in 45 min without feeling you're maxed out effort-wise.
If you're looking to upgrade simply because you want the ease of use/convenience a crank affords you compared to a dropweight, that's fine, too. I guess what I'm saying is be sure you're making the change for the right reasons. Be a bummer to get a crank and discover that you're only saving 5 minutes because you didn't realize you were losing time in other areas.
Need help finding lost dog: walks with a limp, recently castrated, can only see out of one eye - answers to the name, "Lucky".