I think the answer that will help you decide this delima, is how much involvement in testing glucose is your vet going to be?
How often are you visiting?
Are they doing just once a visit tests or are they also doing curves?
Does your vet also recommend a fructosamine test each visit?
For Fabby- we only go to the vet for an issue outside diabetes. We're not regulated with her diabetes yet, rather ups and downs so far. But I understand her readings on my human meter, and use the spreadsheet. When we visit the vet for outside issues the vet takes a look at the spreadsheet, listens to my current plan/path with Fabby and makes suggestions if my plan doesn't work out. But mostly she is thrilled with my diligence in testing at home.
With your vet pushing a pet meter on you, this really sounds like a vet problem not yours or your cat's problem. The point of the spreadsheet is not to take a look at one number for it's exactness, but to find trends, and see what your cat responds best to (food/timing/insulin/etc). If your vet is not looking through your spreadsheet and able to understand it and interpret it, personally, I would question the vet's competence in managing our care. There are vet's that rarely get a diabetic cat in for treatment, which means their experience with treating diabetic cats is limited. I'm not paying the vet bill to be someone's "experience". I pay the bill for expertise.
There may also be the factor that the vet wants you to buy the new expensive meter from them and the strips. While the meter isn't a terrible cost when it comes to all of this, the strips will eat away at you. And if you are getting pet strips from the vet you are paying a premium and they are making a repeat customer for life. My diagnosing vet only saw dollar signs, so I'm wary about this, because it does happen.
So back to the questions...
How often are you visiting:
If you are at your vet quite often, it may get uncomfortable challenging your vet on their recommendations. If you're not there often, then you won't have this problem, stick with your ReliOn and your spreadsheet and you'll do just fine watching trends.
Are they doing just once a visit tests or are they also doing curves?
Once a visit tests at the vet are almost always useless. Your cat's glucose is already high due to the stress of the carrier/car/vet visit, which means you can't trust this number whether it's on a pet meter or a human one. If you're doing curves at home, there is no reason to pay your vet to do them, the numbers will all be higher and again, it's looking for trends. You'll get more accurate numbers at home, leading to better treatment.
If you are leaving the curves up to the vet, and treatment is only going to be based off these numbers then the only reason you need to test at home for is in case of a problem (I don't recommend this route) like hypo. Because if you're not testing to enhance your cat's treatment then it is specifically to ensure you don't have a hypo event.
Does your vet also recommend a fructosamine test each visit?
This is a 60-80 dollar (U.S.) test (which your vet might charge you a hundred or more for) and it will spit back a number. That number is roughly the average blood glucose your cat is at over a time period of 2-3 weeks. As you can see, it's not very accurate. So these too are useless. I asked this question because vet's like to do them. It makes them feel better I think (the vet, not the cat). You could barter with your vet and say, "I'm going to stick with the human meter for now, and on our next visit we can run a glucosamine test to see if my spreadsheet full of numbers tells you the same info that the test does. If there is a discrepancy, I will then move over to the pet meter." This will prove to your vet that a human meter is at least as accurate as their glucosamine test.
The reason we use human meters instead of pet specific ones is cost. The difference in the meter purchase isn't really a big deal when it comes to your pet's health... it's the strips. I use 4 strips a day (provided I NEVER mess one up) which means I require a minimum of 120 a month. I use the ReliOn Confirm, so it costs about $45 to get through the month just in strips. If I used a pet meter, it would cost me over $120 a month - just to test her. That doesn't include any treatment supplies. So, if cost isn't an issue and you don't want to challenge your vet, get the pet meter. But otherwise a human meter does the job just fine. (And only use the glucosamine statement if you don't outright feel comfortable telling your vet no. If you feel find telling your vet if you decide to stick with the human meter, then the glucosamine challenge is just more wasted money.)