All i know about 550Ti is that nouveau with 3.2 does not correctly work, but nouveau with 3.5 works. Most likely you did not compile kernel 3.5 correctly and most likely have got no clue how to install nvidia drivers the right way...
Yes, it may well NOW work but I installed with the first alpha of Ubuntu 12.10 whereby it didn't. It also doesn't work with any released version's of various distro's since those kernels and was like that for many a month. I have been doing dist-update since and it all works fine after manually fixing. Excepting the grub config needing to be fixed manually to include my Windows partition which is to be expected during alpha (why GRUBtwo wont pick up Windows by default is nothing short of annoying to be honest but that's something else). Ultimately I just dont want the Ti550's either. It was meant for a SLI-config but it just didn't perform to expectations (extremely nice gift last year, but one that failed to materialise =(.
I dont bother with compiling a kernel on my main machine because if it doesn't 'just work', then I stay with an older distro-managed version that does. I'm not lazy. I just don't have the time to fuck around with my OS' now that I dont work a tech job. So I need my shit to just work as much as possible, through the upgrade cycle, with minimal human config on the lower-end of the system, beyond tweaking the usual desktop experience. Otherwise, in the coming moths I may have a Ti550 or two up for donation soon enough if this new job works out.
My money is 100% into hardware that will run what I need it to run, and to companies that don't screw me over. That means that INTEL is completely off my list (with the poulsbo fiasco, it will take them a LOT to earn back my trust), and nvidia is definitely off the list (blob driver is totally inadequate).
Considering how Intel remains the most well-supported hardware provider in Linux (with support for the upcoming Haswell already added into the kernel) what trust issues are you talking about?
And NVIDIA's blob has been at performance parity with Windows for a long time. Unless you consider 'performance parity' to be inadequate, I have no idea what benchmarks you base your claims on.