user3219: Do I need to re-install many libraries (or similar 'house keeping' works)? Is the upgrade straight forward?
Apparently, from Arduino web, one need 1.5 BETA series for use with Due. For Pro Mini, UNO and ATMega2560, should one use 1.5 BETA or 1.0.6 (no beta, presumable stable)?
I am running out of code space. Wonder if the upgrade will install a newer gcc compiler and smaller code size? 

user1585: Old libraries will work with 1.5 Beta, but you will most likely need to copy any of your own libraries over to the new beta installation, depending on if they were installed to the sketchbook location or inserted into the installation before. That should be about all you need to do after installing the beta for it to work.
The Beta supports all the regular boards as well as the Due and Yun. I doubt you will see any change in binary size if you update. I've been using the beta for some time now and it has been quite stable.
Which version you should use is up to you, the differences are relatively minor. I think the beta adds a few convenient features, but there are no changes to the code or functionality like the switch to v1.0 made.

user490: I have had trouble with 1.5.7 (Beta), so I would stick with 1.0.6. As for code space, you might want to look into Atmel Studio (Free), which uses a Visual Studio shell as the IDE. It blows the Arduino IDE out-of-water. Atmel is the maker of all the AT chips, so the Atmel Studio IDE is a great IDE for writing AVR code. Lots of tutorials online and there is a Arduino plug in called Visual Micro (Free also).

3219: <p>Do I need to <strong>re-install many libraries</strong> (or similar 'house keeping' works)? Is the upgrade straight forward?</p>

<p>Apparently, from Arduino web, one need 1.5 BETA series for use with Due. For Pro Mini, UNO and ATMega2560, should one use <strong>1.5 BETA or 1.0.6</strong> (no beta, presumable stable)?</p>

<p>I am running out of code space. Wonder if the upgrade will install a <strong>newer gcc</strong> compiler and smaller code size? </p>
 1585: <p>Old libraries will work with 1.5 Beta, but you will most likely need to copy any of your own libraries over to the new beta installation, depending on if they were installed to the sketchbook location or inserted into the installation before. That should be about all you need to do after installing the beta for it to work.</p>

<p>The Beta supports all the regular boards as well as the Due and Yun. I doubt you will see any change in binary size if you update. I've been using the beta for some time now and it has been quite stable.</p>

<p>Which version you should use is up to you, the differences are relatively minor. I think the beta adds a few convenient features, but there are no changes to the code or functionality like the switch to v1.0 made.</p>
 490: <p>I have had trouble with 1.5.7 (Beta), so I would stick with 1.0.6. As for code space, you might want to look into <a href="http://www.atmel.com/tools/atmelstudio.aspx" rel="nofollow">Atmel Studio (Free)</a>, which uses a Visual Studio shell as the IDE. It blows the Arduino IDE out-of-water. Atmel is the maker of all the AT chips, so the Atmel Studio IDE is a great IDE for writing AVR code. Lots of tutorials online and there is a Arduino plug in called <a href="http://www.visualmicro.com/" rel="nofollow">Visual Micro (Free also)</a>.</p>
