So, here are my bikes... First my MTB, in my wife´s position, then in my position. My wife´s position on the bike is realistically too low for her, but she likes it low and it is totally just pottering along with the kids who are only 4 and 5.

I have my position on the MTB almost identical to my Felt Hybrid position, just slightly lower on the seat (ie- seat level to pedals - but only lower by 5mm or so). But you can clearly see how much smaller the MTB frame is to the Hybrid - The hybrid only has a small portion of the seat post showing whilst the MTB has a lot - It´s also a fact that even in my position on the MTB it is not at full height, it could be put up 40mm more to be at the capacity maximum which would totally be far too high for me and my inseam.

I think the fit on both bikes is perfect for me, although in truth I would go to an 18" (460mm) on the MTB if my wife wouldn´t ride it, but having a smaller frame on the MTB makes for easier off roading for me, much easier to chuck around. The 52cm Felt is 100% the correct size for me, 55cm too big and I am 100% sure it would be for you too, you would need the same as me or the slightly smaller 48cm. But this is all based on Felt Hybrid Geometry, others will be slightly different.

Cheers.