In that regard you would be wrong. No photographer would ever argue against getting better glass. My advice about going to a camera store and trying both lenses is sound. His main complaint is the lens is soft at 50mm. By personally comparing both 50s side by side means he makes an informed decision based on his own personal experience. Lab results and other users experiences are useful in helping make that decision but should always be taken with a grain of salt. I'm not sure I follow your reasoning about professional work and practicing either when it comes to lens selection. Care to explain that a little more?
Pro photog here and I would argue against it. In this scenario anyways.
KJ - don't get bogged down with a bunch of gear talk. It's for pros and pixel peepers and gear collectors, IMO. It's too confusing and no one really cares. 50mm 1.8 is great for where it sounds like you're at right now. Upgrade to a 1.4 if you eventually feel like you need to (I will bet money that you never will). 1.4 is unquestionably a better lens, but the 1.8 will get you 98% of the way there. Especially over the garbage Canon kit lenses.
Resale value no good on a 1.8? Perfect, buy one used. Or buy it new and you'll be out a whole 50 bucks if you a sell of a loss of 50% (doubtful). My $125 Nikkor 50mm 1.8 is probably the sharpest lens I own (never made huge prints to compare though......)
I'd also recommend a 35mm on a cropped sensor. I found 50mm frustratingly long most of the time on my crop cameras, but maybe that's just me. Buy whatever and just go shoot.