Hotspotting questions

[Mark]

Right now we have 5 region servers and one of our tables is quite small 
(500k records) therefore it sits all in one region. This is happening 
because we are using a row key that corresponds to a FK in one of our 
MySQL databases so it's sequential in nature. I know the obvious fix for 
this would be to apply some sort of hash function on the rowkey before 
reading/writing but before I go down that route I wanted to know if I 
should bother. When does hot spotting start to become an issue? Would 
you say this is a cause for concern at this time? I should mentioned 
that at this time we are only writing to this table but we will soon be 
going live so it will start receiving get requests.

Thanks for any suggestions.