50MHz is fine for most people. I haven't even cracked my DS1054Z yet.
The 453 has some excellent things about it which people tend not to know about. I'll try and detail them here:
1. They are fully discrete. There are no ICs in the unit at all! Bar the transformer and tube going, it's 100% possible to make these last forever with component subs.
2. All the test points and boards are completely accessible.
3. Was designed to be taken to bits. There are two knobs, one on each side. Undo them and the case just comes off.
4. The service manual is exceptionally good, even for Tektronix.
5. The thing is built like an Apollo spacecraft. Chassis is cast aluminium
6. This: