As I heard from Richard that you have been using Jasco polarimeter and are thinking about replacing it with Rudolph Auto IV.
We had Jasco before too and have changed to Rudolph Auto IV for about a year. We are pleased with the Rudolph Auto IV especially after we use thermal couple to control the cell temperature while we are measuring the sample. A few advantages about Rudolph Auto IV compared to Jasco are as follows from my experience and the responses from our operators.
(1) The tungsten light source with 589nm filter is equivalent to Sodium source in Jasco and much more stable.
(2) Tungsten light source is acceptable to FDA, USP
(3) By using Quartz plate with built in temperature correction is much more convenient than the sucrose solution for calibration.
(4) Has the same printout capability as Jasco with average & standard deviation etc.
(5) I would suggest you to buy a dual thermal couple to measure both water bath temperature and cell temperature while you run the samples. ( e.g. To make sure your cell temperature reaches your desired temp e.g 20 C, you might have to set up your circulation bath water temp of 21-22 C since your room temp does affect your cell temp. But this happens to Jasco too) Overall, Rudolph Auto IV is a stable and easy to use polarimeter. Again, since instrument releases heat, keep your room temp down will help stabilize your cell temp.