Storage won't be much just 60 on phone but you need to delete regularly.
But for a phone with a really comfy large keypad like 1202 and 1203, priced at Rs. 1050, its really worth it.
Check out Nokia 1661 (has additional option of hands free and radio) @ Rs. 1350 which has 250 sms storage if you need higher capacity.
Or Nokia 2323 which has 10mb space for sms'es which is quite large (loads of saved messages). But phone is 2.3k not worth it at all if you only need a SMS'ing machine.
If you wanted to save sms'es all you would need to do is to forward them to the 5800xm phone anyway
So I suggest Nokia 1202 or 1203. Diff b/w them is the keypad goes inwards in 1202 and bulges outwards in 1203. Try both since which to prefer is completely subjective and finger dependent.
Either phone (a "basic phone") has way more comfortable keypad than most other nokia phones I have used to be honest. Big and comfy even for fat fingers like mine. Similar league as Nokia 3110c or 3500c.
Dual sim without reason is pointless.
Yeah its the same spice phone. But qwerty is extremely subjective. Many swear by it (ask QwertyManiac of our forum) others are really uncomfortable with it since it takes a lot of time getting used to. I prefer using T9 dictionary always for messaging since its damn fast.