Gingerbread (GB) and Ice Cream Sandwich (ICS) platforms differ on a technical level. What you need to ask yourself is....Will you go for the new (less stable) User Interface (UI) features on ICS or will you prioritise stability and stay on Gingerbread?
It is well-known that Ice Cream Sandwich is more intensive in terms of memory usage. As smartphones become more capable, applications are becoming more advanced, which means that they require more CPU power, run more network activities and use more RAM. On the other hand, ICS brings a refined UI and some nice new features.
In ICS, the activity manager has a completely new UI, where all running apps are shown as thumbnails in a list. To close an activity, you can call it out of the list. ICS also introduces a face recognition app as a way to unlock the phone, called Face Unlock. Face Unlock uses the front-facing camera and advanced object recognition algorithms.
The contact list will show more information about the contacts, including updates from social networks. In the calendar, color coding has been added and it is now possible to zoom. There is also support for a new type of voicemail that is more visual, offering transcriptions of voice messages.
All of this translates to more resources being used...
When it comes to ICS, it's a major upgrade of Android, and there are a lot of things that have changed compared to the Gingerbread release. Some of these changes affect the performance and stability of the system, for example by using more CPU power and RAM. ICS was developed with Galaxy Nexus in mind, which is based on a TI platform with dual-core processor and 1GB RAM. Literally double the hardware available on the Marquee. LG would have to adapt ICS to run on the Marquee and build on a single-core processor platform utilizing half the amount RAM ICS was built around. This means that in some cases, the resource usage in ICS will impact the performance of the system and the user experience might not be as good as when running on Gingerbread.
In a 512MB RAM smartphone like the Marquee, about a third is used for functions that require a dedicated memory slot to operate fast enough. The remaining space, which is at least 340MB, is reserved for the Linux user space, as required in the Android Compatibility Definition Document (CDD). Within the Linux user space, functions like the activity manager and Home screen app are running.
Another interesting thing is that many apps use slightly more RAM in ICS. For example, the web browser is quite intensive, and generally uses 20-30MB more in ICS compared to Gingerbread. All in all, there are a lot of changes that together result in greater RAM requirement.
When running low on RAM, typically with less than approximately 40MB left, the activity manager will start to close processes according to priority. At first, idle background activities are killed. The last thing to be closed down is the foreground activity.
Processes that are closed will obviously have to be restarted when the user enters the app again, which takes time and slows the system down.
Another change in ICS compared to Gingerbread is that Google has moved a lot of the SQL handling from the native to the Java layer. Studies have showed that the read and write operations to the SQL database takes longer time, which slows down the apps. Many applications perform a lot of SQL operations when started, which greatly impacts the start-up time.
If an operation takes too long, there is a risk of getting an Application Not Responding (ANR) as a result. An ANR occurs when an application doesn't answer an intent within a certain time limit. In case of intent, the time out is set to five seconds. For the input event, such as screen touch or button click, it's ten seconds. This can result in a user experience that is perceived as slower and less stable, due to longer response times and increased ANRs.
Yet another change in ICS, is that the graphics hardware acceleration is on by default for most apps. Hardware acceleration means that the GPU is used to render graphics, which enables a smooth user interface. However, it also results in a need to load additional graphic libraries for certain apps, which makes them use even more RAM.
Tests on applications showed that the Settings app consumed 1-2MB more RAM, and actually took longer time to start with HW acceleration, compared to without. Once the app is running, the UI is HW accelerated, but unless the app performs advanced graphics, the user will not see the difference.
Another effect of the hardware acceleration is that it can make the battery drain faster in some cases. An example of this is video playback, where the hardware acceleration requires every video frame to be run through the Graphics Processing Unit (GPU), thus making the system use more power than it would have without HW acceleration.
The bottom line is that while it is possible to run ICS on a single-core device (like the nexus S or LG Marquee), the user experience will depreciate in the process.
Your best bet?
Look into the UI aspects you like about ICS and find their Gingerbread equivalent.
for example..like the face unlock feature in ICS? there's an apk for that;
want to unlock the phone while launching into the camera like in ICS?
check out the Go Locker ICS Theme
you can make your gingerbread phone look like ICS without the added hassle of performance lag.