New Bike Purchase, Need help with sizing advice

So I finally got the OK to upgrade from my 1990's Kestrel SCi. I'm looking to purchase a Ridley Damocles from Competitive Cycling. It's all SRAM Force and has pretty decent wheels (Reynolds Solitude) for a very good price I can afford. I can not find a bike of this caliber and components for under $3k anywhere near me, which is why the online purchase.  But I have a few questions.

I know I should go to a LBS. I've tried this and to no avail. They don't have any bikes I can afford which are even near the bike being sold on CC. Plus, I honestly don't trust them as far as fitting because they just sort of eyeball it. I'm 3 inches shorter than my friend and 50 pounds lighter who paid $200 for a pro fit and who was put on a size 56. I went into a shop the other day and asked to ride a 54 or 56 and the owner freaked out on me saying I was defiantly a 58. His rational was that we were the same height and he rides a 58. But he is much older, less flexible, and portly. I tried it out for his sake, but it felt HUGE. So WTF? How can I trust a LBS vs an online shop when this joker obviously had me wrong? Other shops just sort of look at me, raise or lower the seat, and send me out on a ride. This doesn't seem like a fitting to me. Especially when they want me to spend the extra money vs online.

I would love to have a true fit done, with actual measuring tools. But then, my local bike shop would not be local anymore since I would have to drive a couple hours away. Even after I got fitted, I still can't purchase a bike with the specs I want since it would be so expensive. Oh, and the fitting also adds $200 to the price (I don't know where you people get free fits with a purchase cause all the shops I called, it just isn't happening). So, would it be okay to pay for a fitting, but then use whatever numbers they gave me to purchase a bike online? I've read how different bikes will fit differently. But we don't have mega shops where there are like 6 or more different brands to pick from and try out. I have to go shop to shop to try out different brands. Which is where I run into the varied, and crazy, opinions by each store clerk on what bike fits for me.

Another aspect is going to a LBS to ride the bike and get a feel for it. Well, I also have done this and honestly, they all feel great. My current ride is so old and sluggish, that any new bike will feel great, which they do. I think I need to ride a bike made past the 1990's for a couple years until I can properly feel what I want in a new bike. So really, any bike will be better, whether it is purchased at a LBS or online. But am I missing something with this logic?

Last, I'm between size Small and Medium according to the measurements I took and put into the CC fit calculator. Reading online, I found that buying the smaller size is preferred for compact bikes since you can alter the smaller size to make it almost a size bigger, if needed. You can't alter the large size down a size though. But if I did this, I may need to add spacers. What does this do as far as handling? Would my center of gravity be too high up? One shop started to rattle on about having the proper head tube size, and that a smaller bike may not have this. But I didn't know what the heck he was saying since it all just sounded like sales jargon and he wasn't answering my questions, but more just keeping to a script he memorized. So what the heck does head tube size matter?  Won't spacers sort of make the head tube area longer on a smaller bike?