Not really having any radio-related issues - unless you want to count not having the setting for adjusting servo speed linearly like you can with more expensive radios, I guess. I've adjusted steering throw to be equal, the thing really turns on a dime in both directions. I haven't actually been using sub-trim at all, just regular trim. Only really started using EPA etc just in the last couple of months, though strangely enough I made do ok without, but certainly easier to get the steering right by using it after doing physical changes to a car or getting a new car! I only really got deeper into the settings once I got these four new cars (2x offroad SCT, this Mini and a touring car) and started using the same radio for all of them as well as on the older cars as compared to using a dedicated radio per car previously.

I suppose an even more advanced radio would have its benefits, but for as little as those would be for the most part, it's a bit hard to justify. I already can't even seem to justify buying more Sanwa receivers when I have two and can move them around, given they're a bit pricey. Better transmitters... even more pricey (even if you only need the one)

As for the speed issue... I guess I could try the HPI SF-2 servo I removed from my HPI Savage, it's likely to be slower. As would the servo I put in the Savage instead (seeing as I won't be driving it in winter in any case), but it's a bit annoying to remove. The Reedy 1903MG I have would also probably do the job but it'd need a replacement gear set and the local store selling those just went under.