LOL. I go through that with engines all the time. I always end up shying away from the high end engines. I've race off-road for a season now and I'm going to try a high end motor in the next couple of months.
The .21VG is just like you have heard. It runs good, but definately not the fastest. It does lack some bottom end punch for a truggy so I used a JP-1 pipe on mine and I had no complaints. If I would have been on a track with a 200ft straight away I might have run out of motor towards the end, but I would have tried to make up for that teeny tiny disadvantage by driving a tighter line around the track.
If this will be your first nitro engine don't be disappointed if you toast it with in a gallon or two. The words you read on here will not make up for experience. But the more you read the better educated you will become of course. Many, many people have bad luck with their first engines no matter what brand. So for under $200 you won't be out much, all engines can be resleeved when needed, and by then you will have a lot of run time with your car. Then after the rebuild or if you decide on a different engine, you will have the experience to know what the engine wants, and what to do to make it last.
I learned nitro engines with a Revo. The first engine lasted almost a gallon. The second engine was over two gallons and going strong when I sold it. Then I bought a buggy with a Mach 427 (.26) and it's still going good after 13 gallons. That engine is on my oval car now.
Once I start having tuning trouble with my engines is when I look to rebuild/replace. That is if everything is sealed up from air leaks, gaskets are all in place, the fuel tank and carb are in good condition. If it just doesn't run right with all else being good, that is a good indication that the engine is done for.