I ride my 301 in Lake Garda pretty much every day for 6 months, possibly the rockiest place I’ve ever ridden next to Sedona. I use a carbon downtube protector that clips on round the BB shell made by MiRo. I haven’t had any issues apart from one dent that I picked up when I forgot to put the guard back on after washing the bike (rare occassion in Garda!) I’ve done 2 seasons on LV bikes now and in 6 months of riding the only things I have to do on the bike are change the brake pads, which is great as downtime for servicing/repairs is absolutely minimal. The amount of time I spent fettling other bikes in previous years was depressing.
The downtube as well as being butted is also thicker underneath than at the sides. I really don’t think there is any problem with this frame other than cosmetic.
I’ve sent a message to the tech guys at LV though to ask their opinion and also about the warranty/seatpost issue.
If anyone ever needs info/bits/spares/bikes for these let me know, I have plenty, including complete ex demo bikes, new frames, 160mm rocker plates, all spare parts etc etc.