Pinarello Paris advice please

Mazan

Does anyone here have experience with the Paris normal and/or easyfit frames? My daughter needs a new frame, she currently has a Specialized Sequoia (aluminium) size 49 (TT 51.8) that she has had since she was 12 - she is 18 now. Last year she started having lower back problems and we took her for a bike fit, they adjusted a few things including changing thestem for a longer one (110) but said that basically the frame is too small for her and they could not get a perfect fit. We have been looking to upgrade her bike and get a new bike or frame (her bike now has ultegra components and wheels), but we live in South America and there is very little choice available. For example last year there were a few amiras and treks, but all were too small. We could now get a ruby sport in size 51 but the components are not as good as the ones she has....and I think she is after something a bit racier... The other day she saw (and fell in love with) a Pinarello Paris easyfit frame, the cost is about the same as the ruby complete bike, but the shop assistant thought it would be too big for her - it size 51 with TT 54.5. He said he had another Paris bike (NOT easyfit) in another shop in size 50 and on paper the size did seem to be better - TT is 52.5. It was also a 2012 model and less expensive! However when she tried it it did not seem right somehow - the height was OK but she has a long femur and the setback did not seem enough, her knee was way past the pedal center and the seat was already quite far back. So now we wonder whether the 51 easyfit would infact be better.....she is 166.5cm (nearly 5 foot 6) but has inseam 80.5cm (31.7 inches). The length of her arms stretched out finger tip to finger tip is the same as her height. Problem is that the easyfit its just a frame so its difficult to try unless we leave her bike and change over all of the components which they kind of reluctantly offered to do, so if we do this I feel we're almost committed....

I should add that she also sometimes rides my husband´s Roubaix which is size 52 (TT 53.7 with 90 stem) and she likes this a lot better than her bike, at least on longer, flattish rides, I think she prefers hers for climbing. On her bike she is quite upright and it hurts her back more, on the roubaix she is more stretched out, her back is more comfortable though she does have a bit more strain on her wrists and forearms, however its not really set up for her. The reach on the roubaix is given as 379mm, on the Paris easyfit 51 it is 375 and on the Paris 50 it is 372......the ruby 51 is 370......

She trains for inline speed skating (maybe back problems from this rather than bike?), the cycling is part of the training, they usually ride from 4-6 days a week, alternating between "flat" (40-80km generally) and clmbs (12-20km), she is quite strong. She ocasionally takes part in road bike races too.

Sorry this is long but thought I should explain the situation as much as possible. I would be grateful for any advice or feedback.