older CD transport vs newer ones.

I added a fairly inexpensive CD transport to my DCS Rossini DAC/Clock and am shocked how much better it sounds spinning a disc vs streaming it.  It's not even a close call.  I was thinking of bettering my CD transport and was looking at options such at the Jay's CD transport.  There are also options such as Mark Levinson 31.5 which was a 10K unit in it's day.  Any thoughts on the best way to go?  I get a little worried about one of these older units breaking and not being able to get it fixed.  
I can think of three components that vary from transport to transport:

1. Error correction…the better transports can better correct things like scratches, pinholes and other defects.

2.  Jitter.  The better transports will significantly lower the amount of jitter.

3.  Noise.  The better the transport, the less noise that gets output along with the 1s and 0s.  This includes both noise generated by the transport itself, and any induced noises by external vibrations.

have I neglected any other factor on how their sound might differ?
I still use a TechnicsSL-PS840 into a Cyrus Dacmaster (sometimes still use the discmaster transport as well but I think it's living on borrowed time) - the build quality certainly feels good, better than my CXC which although good has been a disappointment compared to the brilliant CX amp and streamer; the tray is nasty, the display looks cheap and you can see the plastic inside- track access is pretty quick though but it just doesn't feel like it will last

OK the Technics digital output is not in the same league as using the Cyrus but as a transport it's a joy to use- beautiful sliding tray, direct track access, good remote, lovely display, headphone output, only downer is it's optical only digital out. It is honestly like an old Mercedes and feels like it will go on forever.
I totally agree, take a very close look at the Pro-Ject RS2 CD BOX Transport. I truly believe it will improve your system.
IMO, if your main concern is having the transport die on you, I would purchase the Jay's Audio with 2 extra transports.  That should hold you for a while. The Pro-Ject is probably great, but, also IMO, the transports come from a new company and you never know where they're going to be in a year, or what the availability of spare parts will be in the future.  With the Jay's and 2 extra transports, at least you know what you got. 
I’m using a Sony CDP-2700 from the mid nineties as my transport and it sounds amazingly better than everything else I’ve tried!

All the best.