She looks good to me, obviously more capable a combat ship than the gangut, but you are right about the speed compared to the Sevas aswell as the obvious level advantage and support slot bonus the Sevas offers. But, imo it would only last 5 levels and then be replaced when you reach the IM
The ebb3 is only 1 level higher though and is considerably better than the Poltova, with the exception of its size, but it has that extra support, it can use the 12" B-36 from the Kronstadt, slightly more DP, better turning, better OH ratio, etc. Too bad it looks like an Izmail :) that said, I would still continue to use it over the IM unless the size really got on my nerves.
However, if I was to recommend a ship, I would say the Stalingrad '53, to bridge the bb4-5 grind. Not that the stalingrad isnt a brilliant ship, but the '53 IS better. Depends, if you want a bb2-3 to help with that grind then I would say the Izmail 1916 which would probably last you until Stalingrad if you can bear it, if you want one to help with the bb4-5 grind I would say the Stalingrad. The poltova though, is still better than the gangut, but not the Sevas, imo.