I built a full-size FTD (Flight Training Device) based on the same MSFS engine as the Pacific Simulators machine. I chose to base mine on a C-172 because I was interested in pilot training, as opposed to entertainment, and because I felt it had more relevance to people learning to fly than a 737 might. I deliberately chose to use 'proper' instruments rather than these new-fangled glass things too because for some time I think that'll be the most likely 'real' cockpit they'd come across
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To my mind the 737-based units are, for the most part, a pure entertainment machine. If you're working for a company that runs 73's then I'm sure they'll have the procedures (that perhaps include simulators) in place for keeping you current so you'd be unlikely to want to pay casual rates for these. Equally you won't be initially learning to fly on 73's so they're not much use there. 172's on the other hand are probably the most common light aircraft in the world and a person using the 172 FTD could easily step into the real thing at their local aero club or whatever. There is I believe a reasonable transfer of learning between the two machines.
In my case the FTD was used by a flying school for instrument training and for dealing with particular VFR problems people were having. It was successful in both roles and of course would be very useful as a procedural trainer. The hourly charge was around half that of the local Flight Experience machine and in my view represented good value at that (it was also somewhat less than the real thing!). I was always somewhat flabbergasted at the idea of putting Simulators in shopping centres and charging as much as they did. They didn't seem to to me to hit the right price point for either the casual person walking by (would you pay $200+/hr on a whim just when you were getting your groceries or whatever?!) or your average 737 Pilot wanting a refresher (who'd surely use the company equipment). That left a few hard-core entertainment freaks or the odd person interested in the technology or wanting a vague idea of what a 737 cockpit looks like. Hardly a recipe for commercial success IMO, I just didn't think the market would sustain it and I rather suspect that has been borne out over time.
So if you're interested in improving your flying education I think you'd get better value for money with the AVGAS route, if however you're interested in an idea as to what it's like to drive a 73, or what can be done with MSFS and some external tech, then go and have a crack at it
FP.