Currently we have approximately 3000+ strings holding 15000+ words in the source language files and therefore I can confirm that ctransifex can save a lot of working hours for (voluntary) language managers of a project.
Jomres comes with LOTS of features and options (Have a look at the Online Manual) which need to be set to your personal/business requirements, so you will have to invest some time to learn how everything works together. If you want to customize the page layout, some basic knowledge of (how to change) HTML, PHP and CSS is helpful.
In case of any problem with Jomres, support from the developer has always been excellent.
Jomres is beeing developed full time, which is a clear advantage over most competitors and if you have a good idea/suggestion which would make Jomres even better, the developer frequently turns it into code with an amazing speed.
In my opinion Jomres is the best value for money you can get if you want to stay in the rental business for quite a while.
Both thumbs up for this one!