If you can afford it, I'd go for the TR6, as from what I hear the continuos fill can come in real handy when you are doing big jobs, other than that the TR5 is IMO a stellar performer. Although on paper, it may only look slightly more powerful than the Saeco, remember that the big dollar units($1300+) really aren't all that much more powerful than the TR5, but the difference is huge. It seems that a little extra PSI, and as little as 10 degrees increase in the boiler temp will provide a lot more cleaning power.
The TR5 is great. I can clean a filthy iinterior in about 1/2 to 1/3 the time it took me without it, and it's probably 20-30% faster on carpets than the Saeco. I was going to recomend a place that had some used units for sale($200 and $300 for the TR5 and TR6 respectively) but they are apprantly out and won't be restocking. If you can find a used one, it costs about $180 to get it fully refurbished, so depending on how cheap you can get it, it may be a better deal than buying one new, the only probably is the turn around time is really long, especially if you pick up an analog version(I won't get mine back for about 4 months).
Is there anything else more specific that you wanted to know?