Regarding service, Vita-Mix has always been fantastic. I'd give them a 5 out of 5. I would expect the same service out of Blendtec, but I just don't have any feedback on that. Vita-Mix does have a better warranty length overall, but in my experience, you truly have to abuse a blender to kill it in under 3 years. For ease of use, I would vote Blendtec until you get the Vita-Mix Blending Station and Touch & Go which would have a slight edge. For Parts, I would vote Blendtec for jars because they start you off with 2 Jars, and it's cheaper to buy a whole new Blendtec Jar than a Vita-Mix. However, I would vote Vita-Mix for the drive socket because you can replace it. The socket on the Blendtec has a lifetime warranty, but you cannot order one for a spare.
Blendtec originally had an edge on frozen drinks because their blade design made a better texture (believe it or not, you can tell), but then Vita-Mix came out with their Advance series of blenders and evened the playing field. Internally, the concept of the blenders is the same-- a heavy duty vacuum cleaner-style motor but with more power, better bearings and balance. If you want to program (or use pre-programmed settings) in your typical drinks and batch sizes, the Blendtec offers more flexibility because their touchpad and digital screen are available on all models, something you don't get on a Vita-Mix until you hit their Touch and Go or Blending Station Advance units (which are a little easier to program). Blendtecs all have the same touchpad though, so if you ever change models, your employees won't have to relearn the controls.
The issue of parts shouldn't be a hurdle with Blendtec. Yes you have to replace the whole jar kit, but a Vita-Mix blade costs $70 and a BPA-Free Blendtec Jar (with blade and lid) costs $80. Blendtec blenders also come with 2 complete Jars out of the box. And again, the socket is an easier replacement on the Vita-Mix. I've replaced motors on Vita-Mix blenders before, and they last well beyond their warranty if operators are not abusing the blender. Blendtec should be the same. Sometimes what you'll see is that an employee might make a drink too thick by adding too much ice for the blending cycle. Instead of thinning it out with a little water or milk (or some other base), they rock the jar or try to shake the entire blender. This puts all the torque on the bearings, and at such high RPM's, doing so will shorten the life of the blender. As an entrepreneur, you already understand how to value your capital, but an average employee does not see the blender as a profit center, just a tool that will be replaced if broken.
For a commercial blender, it would really depend on what setup you want and how much traffic the store would see. Blendtec's 20 Amp Smoother can handle more work than everything except Vita-Mix's new beast of a blender, the XL Blender (which may or not be practical for your stores). If you predict that you will be making batches of drinks more often than single drinks (based on your menu), I would go with the Blendtec with at least a 15 Amp model because they can use the 96 ounce jars. If you are making single 16 ounce drinks at a time and not in rapid succession, I would focus more on price than features because you won't get as much of a return on your investment with the higher-powered Blendtecs or the Vita-Mix Blending Station Advance.
You must also decide on if you are looking to install 2 or 3 (or more) blenders, so you must factor in how much countertop space you will need, and also how much overhead clearance if you have shelves over the blenders or want units with a sound enclosure (highly recommended). Also, if you are wanting to mount your equipment into the countertop rather than sitting on the counter, Blendtec offers more versatility because both their Smoother and SpaceSaver can do both while certain Vita-Mix blenders can do one or the other. If you are using powder mixes such as Big Train, I'd definitely recommend the in-counter mount because those cooling fans draw a lot of air, and that powder will cake all over the motor.
