Hi soccerlover17,
It would depend to some degree on the type of support system you have under a mattress and any additional risk factors that are in your environment. They certainly wouldn’t be necessary with a slatted foundation or platform bed under the mattress but if you have a solid surface support system that doesn’t provide any ventilation underneath the mattress it can add to the risk of developing mold or mildew in the mattress although in most cases it would still be fine (see post #10 here).
Urban Green is just the new website for Foam Sweet Foam and their mattresses on the Urban Green site are the same. A forum search on foamsweetfoam or on FSF or a specific term site search on Foam Sweet Foam (you can just click the links) will bring up many more comments and feedback about them.
While other people’s comments about the knowledge and service of a particular business can certainly be very helpful … I would be very cautious about about using other people’s experiences or reviews on a mattress (either positive or negative) as a reliable source of information or guidance about how you will feel on the same mattress or how suitable or how durable a mattress may be for you and in many if not most cases they can be more misleading than helpful because any mattress that would be a perfect choice for one person or even a larger group of people may be completely unsuitable for someone else to sleep on (see post #13 here).
I would also keep in mind that the length of a warranty of a mattress has very little to do with the useful life of a mattress and how long it may be before you need to replace it. Warranties only cover defects in a mattress and not the gradual (or often rapid in the case of lower quality materials) loss of comfort and support that is the main reason people will need to replace their mattress. There is more about mattress warranties in post #174 here.
While there is no way to quantify how long any mattress will last for a specific person or predict exactly when you will decide to replace it because it is no longer suitable or comfortable for you (because this is the only real measure of durability or the useful life of a mattress that really matters) because there are too many unknowns and variables involved that are unique to each person … if a mattress is well inside a suitable comfort/support range and isn’t close to the edge of being too soft when it is new (see post #2 here) and meets the minimum quality/durability specs that are suggested in the guidelines here then it would be reasonable to expect a useful lifetime in the range of 7 - 10 years and with higher quality and more durable materials like latex or higher density memory foam or polyfoam (in the comfort layers especially) it would likely be in the higher end of the range or even longer.
Component mattresses also have some advantages because they allow you to “fine tune” the comfort or support of a mattress both before a purchase and after a purchase (either by rearranging layers or exchanging layers or components) and if one of the layers softens or breaks down before the others (usually one of the softer upper layers) or if your needs or preferences change over time you can just replace a single layer or component instead of replacing the whole mattress.
As you probably know from your reading here Foam Sweet Foam is a member of this site which means that I think very highly of them and that I believe that they compete well with the best in the industry in terms of their quality, value, service, and transparency and you are certainly looking in a great direction.
Phoenix