Glad you’re loving it. Faulty rear shock aside, mine has been brilliant. In a straight line, it’s super stable, begs to go faster and is surprisingly playful/poppy. Pedals and climbs reasonably well, although it’s noticeably slower and harder work in this respect, compared to my old Whyte T130.
The angles are great and the spec is brilliant for the money. I also love the low standover and low seat tube.
I went for a medium at 5’10” of average proportions. Torn for a long time on medium or large, after a test ride but having spent more time with my medium, I am certain it’s the right choice. It’s such a long, stable, roomy bike anyway, that the last thing I want is yet more length. While it’s a playful bike in terms of suspension, it’s not a particularly agile bike in terms of turning, and takes the long way round compared to shorter bikes. Even on a medium with a 40mm stem, I consciously have to get my weight forward far more than my old bikes, which feels good, but a Large would involve that much more forward weighting. Out of interest, I decided to hop on my mate’s Lapierre Zesty (2013) and my other mate’s Cube Stereo (2012) – both Medium. They felt TINY compared to my Medium Aeris. Cramped, nervous, short, albeit more agile. My other mate’s Large Orange Alpine (2014) felt comparable in size though.
If I was 5’11.5” upwards, I’d have probably gone for a Large, like the op has though. Although even then, the medium wouldn’t be small. But I am just pleased that the Medium is sized how it is. For my dimensions, the seat tube is just right (allowing for a 150mm reverb), giving loads of standover, but that is combined with a long 620mm top tube/448mm reach and good angles. Before this, bikes have always been a compromise. My T130 involved sizing up to a Large, but that was married to a seat tube, which was just that too long for getting the saddle properly out the way. I grew tired of banging my balls on the back of the saddle!