I do like and recommend the 1.8 TSI because of the bigger brakes and multi-link rear suspension. Power wise 1.4 TSI is more than adequate and it is the more sophisticated engine because of ACT.
I also had a similar decision to make this time last year.
I'd had a 1.8 Tsi for nearly 4 years and was thinking of changing it for another after the facelift. SEAT initially didn't offer the 1.8 in the UK and when my dealer tried to order one for me it wasn't available on the system to order this time last year. At the time SEAT actually said that it wasn't going to be available. Their indecision eventually lost them a sale!
Whilst looking at the 1.4 Tsi instead, I discovered that VW were at the time doing a fantastic offer on Golfs, selling their pre facelift models off with almost a £3,000 discount.
I managed to get a VW Golf GT Edition for no more than I was going to pay for a SEAT FR. This has the 1.4 ACT engine, the bigger brakes and multilink rear suspension plus it came with 18 inch wheels, front and rear parking sensors, adaptive cruise control etc all as standard. It's a great combination getting the better brakes, suspension etc with the 1.4 engine. Also really liking the DSG gearbox. The only thing I really miss from by 1.8 SEAT FR are the LED lights. I'm not really noticing a significant difference between the 1.8 and 1.4 engines but I am enjoying getting almost 10 mpg more and the cheaper road tax etc.
I notice some people are saying on here that the used 1.8's are selling at a cheaper price than 1.4's. I'm not surprised as the depreciation on my last 1.8 FR was unbelievable. Hopefully going for a VW Golf will
help that situation in 3-4 years time when I next exchange my car.